diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TClass.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TClass.java
index f27377f16..4689e6438 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TClass.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TClass.java
@@ -560,7 +560,7 @@ public class TClass<T> extends TObject implements TAnnotatedElement {
     @SuppressWarnings("unchecked")
     public T cast(TObject obj) {
         if (obj != null && !isAssignableFrom((TClass<?>) (Object) obj.getClass())) {
-            throw new TClassCastException(obj.getClass().getName() + " is not subtype of " + name);
+            throw new TClassCastException(obj.getClass().getName() + " is not subtype of " + getName());
         }
         return (T) obj;
     }
diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java
index e54364c60..376469c35 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java
@@ -185,7 +185,7 @@ public class TObject {
         }
     }
 
-    boolean isEmptyMonitor() {
+    final boolean isEmptyMonitor() {
         Monitor monitor = this.monitor;
         if (monitor == null) {
             return true;
@@ -246,7 +246,7 @@ public class TObject {
         return getClass().getName() + "@" + TInteger.toHexString(identity());
     }
 
-    int identity() {
+    final int identity() {
         if (PlatformDetector.isLowLevel()) {
             Monitor monitor = this.monitor;
             if (monitor == null) {
diff --git a/core/src/main/java/org/teavm/backend/c/CTarget.java b/core/src/main/java/org/teavm/backend/c/CTarget.java
index 99d1a800c..de79e69dd 100644
--- a/core/src/main/java/org/teavm/backend/c/CTarget.java
+++ b/core/src/main/java/org/teavm/backend/c/CTarget.java
@@ -27,7 +27,6 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Deque;
 import java.util.HashSet;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -100,6 +99,7 @@ import org.teavm.model.MethodReference;
 import org.teavm.model.Program;
 import org.teavm.model.ValueType;
 import org.teavm.model.classes.TagRegistry;
+import org.teavm.model.classes.VirtualTableBuilder;
 import org.teavm.model.classes.VirtualTableProvider;
 import org.teavm.model.instructions.CloneArrayInstruction;
 import org.teavm.model.instructions.InvocationType;
@@ -115,6 +115,8 @@ import org.teavm.model.lowlevel.ShadowStackTransformer;
 import org.teavm.model.transformation.ClassPatch;
 import org.teavm.model.util.AsyncMethodFinder;
 import org.teavm.runtime.Allocator;
+import org.teavm.runtime.CallSite;
+import org.teavm.runtime.CallSiteLocation;
 import org.teavm.runtime.EventQueue;
 import org.teavm.runtime.ExceptionHandling;
 import org.teavm.runtime.Fiber;
@@ -266,6 +268,9 @@ public class CTarget implements TeaVMTarget, TeaVMCHost {
             }
         }
 
+        dependencyAnalyzer.linkClass(CallSite.class.getName());
+        dependencyAnalyzer.linkClass(CallSiteLocation.class.getName());
+
         dependencyAnalyzer.addDependencyListener(new ExceptionHandlingDependencyListener());
     }
 
@@ -535,7 +540,14 @@ public class CTarget implements TeaVMTarget, TeaVMCHost {
     }
 
     private VirtualTableProvider createVirtualTableProvider(ListableClassHolderSource classes) {
-        Set<MethodReference> virtualMethods = new LinkedHashSet<>();
+        VirtualTableBuilder builder = new VirtualTableBuilder(classes);
+        builder.setMethodsUsedAtCallSites(getMethodsUsedOnCallSites(classes));
+        builder.setMethodCalledVirtually(controller::isVirtual);
+        return builder.build();
+    }
+
+    private Set<MethodReference> getMethodsUsedOnCallSites(ListableClassHolderSource classes) {
+        Set<MethodReference> virtualMethods = new HashSet<>();
 
         for (String className : classes.getClassNames()) {
             ClassHolder cls = classes.get(className);
@@ -560,7 +572,7 @@ public class CTarget implements TeaVMTarget, TeaVMCHost {
             }
         }
 
-        return new VirtualTableProvider(classes, virtualMethods, controller::isVirtual);
+        return virtualMethods;
     }
 
     private void generateSpecialFunctions(GenerationContext context, CodeWriter writer) {
@@ -631,6 +643,10 @@ public class CTarget implements TeaVMTarget, TeaVMCHost {
     private void generateAllFile(ListableClassHolderSource classes, List<? extends ValueType> types,
             BuildTarget buildTarget) throws IOException {
         BufferedCodeWriter writer = new BufferedCodeWriter(false);
+        writer.println("#define _XOPEN_SOURCE");
+        writer.println("#define __USE_XOPEN");
+        writer.println("#define _GNU_SOURCE");
+
         IncludeManager includes = new SimpleIncludeManager(writer);
         includes.init("all.c");
         includes.includePath("runtime.c");
diff --git a/core/src/main/java/org/teavm/backend/c/analyze/InteropDependencyListener.java b/core/src/main/java/org/teavm/backend/c/analyze/InteropDependencyListener.java
index d24dee91f..73f061733 100644
--- a/core/src/main/java/org/teavm/backend/c/analyze/InteropDependencyListener.java
+++ b/core/src/main/java/org/teavm/backend/c/analyze/InteropDependencyListener.java
@@ -24,6 +24,8 @@ import org.teavm.model.AnnotationReader;
 import org.teavm.model.ClassReader;
 import org.teavm.model.ElementModifier;
 import org.teavm.model.FieldReader;
+import org.teavm.model.MethodReference;
+import org.teavm.model.ValueType;
 
 public class InteropDependencyListener extends AbstractDependencyListener {
     @Override
@@ -31,11 +33,16 @@ public class InteropDependencyListener extends AbstractDependencyListener {
         if (agent.getClassHierarchy().isSuperType(Structure.class.getName(), className, false)) {
             ClassReader cls = agent.getClassSource().get(className);
             if (cls != null) {
-                for (FieldReader field : cls.getFields()) {
-                    if (!field.hasModifier(ElementModifier.STATIC)) {
-                        agent.linkField(field.getReference());
-                    }
-                }
+                reachFields(agent, cls);
+            }
+        }
+    }
+
+    private void reachFields(DependencyAgent agent, ClassReader cls) {
+        for (FieldReader field : cls.getFields()) {
+            if (!field.hasModifier(ElementModifier.STATIC)) {
+                agent.linkField(field.getReference());
+                reachType(agent, field.getType());
             }
         }
     }
@@ -51,8 +58,22 @@ public class InteropDependencyListener extends AbstractDependencyListener {
             return;
         }
 
-        if (method.getReference().getReturnType().isObject("java.lang.String")) {
+        MethodReference reference = method.getReference();
+        if (reference.getReturnType().isObject("java.lang.String")) {
             method.getResult().propagate(agent.getType("java.lang.String"));
         }
+
+        for (int i = 0; i < reference.parameterCount(); ++i) {
+            reachType(agent, reference.parameterType(i));
+        }
+    }
+
+    private void reachType(DependencyAgent agent, ValueType type) {
+        if (type instanceof ValueType.Object) {
+            String fieldClassName = ((ValueType.Object) type).getClassName();
+            if (agent.getClassHierarchy().isSuperType(Structure.class.getName(), fieldClassName, false)) {
+                agent.linkClass(fieldClassName);
+            }
+        }
     }
 }
diff --git a/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java b/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
index ee83423a1..18a320f11 100644
--- a/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
@@ -18,7 +18,6 @@ package org.teavm.backend.c.generate;
 import java.io.IOException;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
@@ -436,7 +435,9 @@ public class ClassGenerator {
         } else if (type instanceof ValueType.Array) {
             className = "java.lang.Object";
         }
-        String structName = className != null
+        ClassReader cls = className != null ? context.getClassSource().get(className) : null;
+
+        String structName = className != null && (cls == null || !cls.hasModifier(ElementModifier.INTERFACE))
                 ? context.getNames().forClassClass(className)
                 : "TeaVM_Class";
         if (className != null) {
@@ -444,7 +445,6 @@ public class ClassGenerator {
         }
         String name = context.getNames().forClassInstance(type);
 
-        ClassReader cls = className != null ? context.getClassSource().get(className) : null;
         String enumConstants;
         if (cls != null && cls.hasModifier(ElementModifier.ENUM)) {
             enumConstants = writeEnumConstants(cls, name);
@@ -459,29 +459,15 @@ public class ClassGenerator {
         codeWriter.print("alignas(8) ").print(structName).print(" ").print(name).println(" = {").indent();
 
         if (className != null) {
-            codeWriter.println(".parent = {").indent();
-            generateRuntimeClassInitializer(type, enumConstants);
-            codeWriter.outdent().println("},");
-
             VirtualTable virtualTable = context.getVirtualTableProvider().lookup(className);
-            if (virtualTable != null) {
-                List<VirtualTableEntry> entries = new ArrayList<>(virtualTable.getEntries().values());
-                for (int i = 0; i < entries.size(); ++i) {
-                    VirtualTableEntry entry = entries.get(i);
-                    String methodName = context.getNames().forVirtualMethod(
-                            new MethodReference(className, entry.getMethod()));
-                    String implName = entry.getImplementor() != null
-                            ? "&" + context.getNames().forMethod(entry.getImplementor())
-                            : "NULL";
-                    if (entry.getImplementor() != null) {
-                        includes.includeClass(entry.getImplementor().getClassName());
-                    }
-                    codeWriter.print(".").print(methodName).print(" = ").print(implName);
-                    if (i < entries.size() - 1) {
-                        codeWriter.print(",");
-                    }
-                    codeWriter.println();
-                }
+            if (cls.hasModifier(ElementModifier.INTERFACE)) {
+                generateRuntimeClassInitializer(type, enumConstants);
+            } else if (virtualTable != null) {
+                generateVirtualTableContent(virtualTable, virtualTable, type, enumConstants);
+            } else {
+                codeWriter.println(".parent = {").indent();
+                generateRuntimeClassInitializer(type, enumConstants);
+                codeWriter.outdent().println("}");
             }
         } else {
             generateRuntimeClassInitializer(type, enumConstants);
@@ -490,6 +476,34 @@ public class ClassGenerator {
         codeWriter.outdent().println("};");
     }
 
+    private void generateVirtualTableContent(VirtualTable current, VirtualTable original, ValueType type,
+            String enumConstants) {
+        codeWriter.println(".parent = {").indent();
+        if (current.getParent() == null) {
+            generateRuntimeClassInitializer(type, enumConstants);
+        } else {
+            generateVirtualTableContent(current.getParent(), original, type, enumConstants);
+        }
+        codeWriter.outdent().print("}");
+
+        for (MethodDescriptor method : current.getMethods()) {
+            if (method == null) {
+                continue;
+            }
+            VirtualTableEntry entry = original.getEntry(method);
+            if (entry == null) {
+                continue;
+            }
+
+            codeWriter.println(",");
+            String methodName = context.getNames().forVirtualMethod(method);
+            String implName = "&" + context.getNames().forMethod(entry.getImplementor());
+            includes.includeClass(entry.getImplementor().getClassName());
+            codeWriter.print(".").print(methodName).print(" = ").print(implName);
+        }
+        codeWriter.println();
+    }
+
     private String writeEnumConstants(ClassReader cls, String baseName) {
         List<FieldReader> fields = cls.getFields().stream()
                 .filter(f -> f.hasModifier(ElementModifier.ENUM))
@@ -633,17 +647,30 @@ public class ClassGenerator {
         String name = context.getNames().forClassClass(className);
 
         headerWriter.print("typedef struct ").print(name).println(" {").indent();
-        headerWriter.println("TeaVM_Class parent;");
 
         VirtualTable virtualTable = context.getVirtualTableProvider().lookup(className);
         if (virtualTable != null) {
-            for (VirtualTableEntry entry : virtualTable.getEntries().values()) {
-                String methodName = context.getNames().forVirtualMethod(
-                        new MethodReference(className, entry.getMethod()));
-                headerWriter.printType(entry.getMethod().getResultType())
-                        .print(" (*").print(methodName).print(")(");
-                codeGenerator.generateMethodParameters(headerWriter, entry.getMethod(), false, false);
-                headerWriter.println(");");
+            String parentName = "TeaVM_Class";
+            int index = 0;
+            if (virtualTable.getParent() != null) {
+                headerIncludes.includeClass(virtualTable.getParent().getClassName());
+                parentName = context.getNames().forClassClass(virtualTable.getParent().getClassName());
+                index = virtualTable.getParent().size();
+            }
+
+            headerWriter.println(parentName + " parent;");
+            int padIndex = 0;
+            for (MethodDescriptor method : virtualTable.getMethods()) {
+                if (method != null) {
+                    String methodName = context.getNames().forVirtualMethod(method);
+                    headerWriter.printType(method.getResultType())
+                            .print(" (*").print(methodName).print(")(");
+                    codeGenerator.generateMethodParameters(headerWriter, method, false, false);
+                    headerWriter.print(")");
+                } else {
+                    headerWriter.print("void (*pad" + padIndex++ + ")()");
+                }
+                headerWriter.println("; // " + index++);
             }
         }
 
diff --git a/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java b/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java
index 1dd02b3c6..86fe439f0 100644
--- a/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java
+++ b/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java
@@ -422,87 +422,17 @@ public class CodeGenerationVisitor implements ExprVisitor, StatementVisitor {
 
         pushLocation(expr.getLocation());
         switch (expr.getType()) {
-            case CONSTRUCTOR: {
-                String receiver = allocTemporaryVariable(CVariableType.PTR);
-                writer.print("(" + receiver + " = ");
-                allocObject(expr.getMethod().getClassName());
-                writer.print(", ");
-
-                MethodReader method = context.getClassSource().resolve(expr.getMethod());
-                MethodReference reference = expr.getMethod();
-                if (method != null) {
-                    reference = method.getReference();
-                }
-
-                includes.includeClass(reference.getClassName());
-                writer.print(names.forMethod(reference));
-
-                writer.print("(" + receiver);
-                for (Expr arg : expr.getArguments()) {
-                    writer.print(", ");
-                    arg.acceptVisitor(this);
-                }
-                writer.print("), " + receiver + ")");
-
-                freeTemporaryVariable(CVariableType.PTR);
-
+            case CONSTRUCTOR:
+                generateCallToConstructor(expr.getMethod(), expr.getArguments());
                 break;
-            }
+
             case SPECIAL:
-            case STATIC: {
-                MethodReader method = context.getClassSource().resolve(expr.getMethod());
-                if (method != null && isWrappedNativeCall(method)) {
-                    generateWrappedNativeCall(method, expr);
-                } else {
-                    MethodReference reference = expr.getMethod();
-                    if (method != null) {
-                        reference = method.getReference();
-                    }
-                    includes.includeClass(reference.getClassName());
-                    writer.print(names.forMethod(reference));
-
-                    writer.print("(");
-                    if (!expr.getArguments().isEmpty()) {
-                        expr.getArguments().get(0).acceptVisitor(this);
-                        for (int i = 1; i < expr.getArguments().size(); ++i) {
-                            writer.print(", ");
-                            expr.getArguments().get(i).acceptVisitor(this);
-                        }
-                    }
-                    writer.print(")");
-                }
-
+            case STATIC:
+                generateDirectCall(expr.getMethod(), expr.getArguments());
                 break;
-            }
+
             case DYNAMIC: {
-                VirtualTable vtable = context.getVirtualTableProvider().lookup(expr.getMethod().getClassName());
-                if (vtable == null || !vtable.getEntries().containsKey(expr.getMethod().getDescriptor())) {
-                    writer.print("(");
-                    for (Expr arg : expr.getArguments()) {
-                        arg.acceptVisitor(this);
-                        writer.print(", ");
-                    }
-                    printDefaultValue(expr.getMethod().getReturnType());
-                    writer.print(")");
-                } else {
-                    String receiver = allocTemporaryVariable(CVariableType.PTR);
-                    writer.print("((").print(receiver).print(" = ");
-                    expr.getArguments().get(0).acceptVisitor(this);
-
-                    includes.includeClass(expr.getMethod().getClassName());
-                    writer.print("), TEAVM_METHOD(")
-                            .print(receiver).print(", ")
-                            .print(names.forClassClass(expr.getMethod().getClassName())).print(", ")
-                            .print(names.forVirtualMethod(expr.getMethod()))
-                            .print(")(").print(receiver);
-                    for (int i = 1; i < expr.getArguments().size(); ++i) {
-                        writer.print(", ");
-                        expr.getArguments().get(i).acceptVisitor(this);
-                    }
-                    writer.print("))");
-
-                    freeTemporaryVariable(CVariableType.PTR);
-                }
+                generateVirtualCall(expr.getMethod(), expr.getArguments());
                 break;
             }
         }
@@ -510,7 +440,100 @@ public class CodeGenerationVisitor implements ExprVisitor, StatementVisitor {
         popLocation(expr.getLocation());
     }
 
-    private void generateWrappedNativeCall(MethodReader method, InvocationExpr expr) {
+    private void generateCallToConstructor(MethodReference reference, List<? extends Expr> arguments) {
+        String receiver = allocTemporaryVariable(CVariableType.PTR);
+        writer.print("(" + receiver + " = ");
+        allocObject(reference.getClassName());
+        writer.print(", ");
+
+        MethodReader method = context.getClassSource().resolve(reference);
+        if (method != null) {
+            reference = method.getReference();
+        }
+
+        includes.includeClass(reference.getClassName());
+        writer.print(names.forMethod(reference));
+
+        writer.print("(" + receiver);
+        for (Expr arg : arguments) {
+            writer.print(", ");
+            arg.acceptVisitor(this);
+        }
+        writer.print("), " + receiver + ")");
+
+        freeTemporaryVariable(CVariableType.PTR);
+    }
+
+    private void generateDirectCall(MethodReference reference, List<? extends Expr> arguments) {
+        MethodReader method = context.getClassSource().resolve(reference);
+        if (method != null && isWrappedNativeCall(method)) {
+            generateWrappedNativeCall(method, arguments);
+        } else {
+            if (method == null || method.hasModifier(ElementModifier.ABSTRACT)) {
+                generateNoMethodCall(reference, arguments);
+                return;
+            }
+
+            reference = method.getReference();
+            includes.includeClass(reference.getClassName());
+            writer.print(names.forMethod(reference));
+
+            writer.print("(");
+            if (!arguments.isEmpty()) {
+                arguments.get(0).acceptVisitor(this);
+                for (int i = 1; i < arguments.size(); ++i) {
+                    writer.print(", ");
+                    arguments.get(i).acceptVisitor(this);
+                }
+            }
+            writer.print(")");
+        }
+    }
+
+    private void generateVirtualCall(MethodReference reference, List<? extends Expr> arguments) {
+        VirtualTable vtable = context.getVirtualTableProvider().lookup(reference.getClassName());
+        String vtableClass = null;
+        if (vtable != null) {
+            VirtualTable containingVt = vtable.findMethodContainer(reference.getDescriptor());
+            if (containingVt != null) {
+                vtableClass = containingVt.getClassName();
+            }
+        }
+        if (vtableClass == null) {
+            generateNoMethodCall(reference, arguments);
+            return;
+        }
+
+        String receiver = allocTemporaryVariable(CVariableType.PTR);
+        writer.print("((").print(receiver).print(" = ");
+        arguments.get(0).acceptVisitor(this);
+
+        includes.includeClass(vtableClass);
+        writer.print("), TEAVM_METHOD(")
+                .print(receiver).print(", ")
+                .print(names.forClassClass(vtableClass)).print(", ")
+                .print(names.forVirtualMethod(reference.getDescriptor()))
+                .print(")(").print(receiver);
+        for (int i = 1; i < arguments.size(); ++i) {
+            writer.print(", ");
+            arguments.get(i).acceptVisitor(this);
+        }
+        writer.print("))");
+
+        freeTemporaryVariable(CVariableType.PTR);
+    }
+
+    private void generateNoMethodCall(MethodReference reference, List<? extends Expr> arguments) {
+        writer.print("(");
+        for (Expr arg : arguments) {
+            arg.acceptVisitor(this);
+            writer.print(", ");
+        }
+        printDefaultValue(reference.getReturnType());
+        writer.print(")");
+    }
+
+    private void generateWrappedNativeCall(MethodReader method, List<? extends Expr> arguments) {
         List<String> temporaries = new ArrayList<>();
         List<String> stringTemporaries = new ArrayList<>();
         String resultTmp = null;
@@ -518,13 +541,13 @@ public class CodeGenerationVisitor implements ExprVisitor, StatementVisitor {
             resultTmp = allocTemporaryVariable(typeToCType(method.getResultType()));
         }
 
-        for (int i = 0; i < expr.getArguments().size(); ++i) {
+        for (int i = 0; i < arguments.size(); ++i) {
             temporaries.add(allocTemporaryVariable(parameterTypeForCall(method, i)));
         }
         boolean stringResult = method.getResultType().isObject(String.class);
 
         writer.print("(");
-        for (int i = 0; i < expr.getArguments().size(); ++i) {
+        for (int i = 0; i < arguments.size(); ++i) {
             String tmp = temporaries.get(i);
             writer.print(tmp + " = ");
             ValueType type = method.hasModifier(ElementModifier.STATIC)
@@ -532,23 +555,23 @@ public class CodeGenerationVisitor implements ExprVisitor, StatementVisitor {
                     : i == 0 ? ValueType.object(method.getOwnerName()) : method.parameterType(i - 1);
             if (type.isObject(String.class)) {
                 writer.print("teavm_stringToC(");
-                expr.getArguments().get(i).acceptVisitor(this);
+                arguments.get(i).acceptVisitor(this);
                 writer.print(")");
                 stringTemporaries.add(tmp);
             } else if (isPrimitiveArray(type)) {
                 writer.print("TEAVM_ARRAY_DATAN(");
-                expr.getArguments().get(i).acceptVisitor(this);
+                arguments.get(i).acceptVisitor(this);
                 writer.print(", ").printStrictType(((ValueType.Array) type).getItemType()).print(")");
             } else if (isPrimitiveBuffer(type)) {
                 writer.print("TEAVM_ARRAY_DATA(TEAVM_FIELD(");
                 String typeName = ((ValueType.Object) type).getClassName();
-                expr.getArguments().get(i).acceptVisitor(this);
+                arguments.get(i).acceptVisitor(this);
                 includes.includeClass(typeName);
                 writer.print(", ").print(names.forClass(typeName)).print(", ")
                         .print(names.forMemberField(new FieldReference(typeName, "array"))).print(")");
                 writer.print(", ").print(BUFFER_TYPES.get(typeName)).print(")");
             } else {
-                expr.getArguments().get(i).acceptVisitor(this);
+                arguments.get(i).acceptVisitor(this);
             }
 
             writer.print(", ");
diff --git a/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java b/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java
index 0c9b60639..4f640dc01 100644
--- a/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java
+++ b/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java
@@ -239,6 +239,13 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
         dep.use();
 
         dependencyAnalyzer.linkField(new FieldReference(String.class.getName(), "characters"));
+        dependencyAnalyzer.linkMethod(new MethodReference(String.class, "hashCode", int.class))
+                .propagate(0, "java.lang.String")
+                .use();
+        dependencyAnalyzer.linkMethod(new MethodReference(String.class, "equals", Object.class, boolean.class))
+                .propagate(0, "java.lang.String")
+                .propagate(1, "java.lang.String")
+                .use();
 
         dependencyAnalyzer.linkMethod(new MethodReference(Object.class, "clone", Object.class));
         MethodDependency exceptionCons = dependencyAnalyzer.linkMethod(new MethodReference(
diff --git a/core/src/main/java/org/teavm/backend/lowlevel/generate/LowLevelNameProvider.java b/core/src/main/java/org/teavm/backend/lowlevel/generate/LowLevelNameProvider.java
index 2424ce06c..8662ee494 100644
--- a/core/src/main/java/org/teavm/backend/lowlevel/generate/LowLevelNameProvider.java
+++ b/core/src/main/java/org/teavm/backend/lowlevel/generate/LowLevelNameProvider.java
@@ -26,6 +26,7 @@ import org.teavm.interop.Import;
 import org.teavm.model.AnnotationReader;
 import org.teavm.model.ClassReaderSource;
 import org.teavm.model.FieldReference;
+import org.teavm.model.MethodDescriptor;
 import org.teavm.model.MethodReader;
 import org.teavm.model.MethodReference;
 import org.teavm.model.ValueType;
@@ -34,11 +35,11 @@ public abstract class LowLevelNameProvider {
     private ClassReaderSource classSource;
 
     protected Set<String> occupiedTopLevelNames = new HashSet<>();
-    protected Map<String, Set<String>> occupiedVtableNames = new HashMap<>();
+    protected Set<String> occupiedVtableNames = new HashSet<>();
     protected Map<String, Set<String>> occupiedClassNames = new HashMap<>();
 
     protected Map<MethodReference, String> methodNames = new HashMap<>();
-    protected Map<MethodReference, String> virtualMethodNames = new HashMap<>();
+    protected Map<MethodDescriptor, String> virtualMethodNames = new HashMap<>();
 
     protected Map<FieldReference, String> staticFieldNames = new HashMap<>();
     protected Map<FieldReference, String> memberFieldNames = new HashMap<>();
@@ -50,7 +51,6 @@ public abstract class LowLevelNameProvider {
     protected Map<ValueType, String> classInstanceNames = new HashMap<>();
     protected Map<ValueType, String> supertypeNames = new HashMap<>();
 
-
     public LowLevelNameProvider(ClassReaderSource classSource) {
         this.classSource = classSource;
     }
@@ -62,11 +62,10 @@ public abstract class LowLevelNameProvider {
         });
     }
 
-    public String forVirtualMethod(MethodReference method) {
+    public String forVirtualMethod(MethodDescriptor method) {
         return virtualMethodNames.computeIfAbsent(method, k -> {
-            Set<String> occupied = occupiedVtableNames.computeIfAbsent(k.getClassName(),
-                    c -> new HashSet<>(Arrays.asList("parent")));
-            return pickUnoccupied("virt_" + k.getName(), occupied);
+            Set<String> occupied = occupiedVtableNames;
+            return pickUnoccupied("virt_" + sanitize(k.getName()), occupied);
         });
     }
 
diff --git a/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java b/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java
index be771a14a..7d81dbd0b 100644
--- a/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java
+++ b/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java
@@ -123,6 +123,7 @@ import org.teavm.model.MethodReference;
 import org.teavm.model.Program;
 import org.teavm.model.ValueType;
 import org.teavm.model.classes.TagRegistry;
+import org.teavm.model.classes.VirtualTableBuilder;
 import org.teavm.model.classes.VirtualTableProvider;
 import org.teavm.model.instructions.CloneArrayInstruction;
 import org.teavm.model.instructions.InvocationType;
@@ -776,6 +777,13 @@ public class WasmTarget implements TeaVMTarget, TeaVMWasmHost {
     }
 
     private VirtualTableProvider createVirtualTableProvider(ListableClassHolderSource classes) {
+        VirtualTableBuilder builder = new VirtualTableBuilder(classes);
+        builder.setMethodsUsedAtCallSites(getMethodsUsedOnCallSites(classes));
+        builder.setMethodCalledVirtually(controller::isVirtual);
+        return builder.build();
+    }
+
+    private Set<MethodReference> getMethodsUsedOnCallSites(ListableClassHolderSource classes) {
         Set<MethodReference> virtualMethods = new HashSet<>();
 
         for (String className : classes.getClassNames()) {
@@ -801,7 +809,7 @@ public class WasmTarget implements TeaVMTarget, TeaVMWasmHost {
             }
         }
 
-        return new VirtualTableProvider(classes, virtualMethods, controller::isVirtual);
+        return virtualMethods;
     }
 
     @Override
diff --git a/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java b/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java
index e0461dedc..5d50cf5a3 100644
--- a/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java
@@ -163,7 +163,7 @@ public class WasmClassGenerator {
             ClassBinaryData itemBinaryData = binaryDataMap.get(itemType);
 
             VirtualTable vtable = vtableProvider.lookup("java.lang.Object");
-            int vtableSize = vtable != null ? vtable.getEntries().size() : 0;
+            int vtableSize = vtable != null ? vtable.size() : 0;
             DataType arrayType = new DataArray(DataPrimitives.INT, vtableSize);
             DataValue wrapper = new DataStructure((byte) 0, classStructure, arrayType).createValue();
 
@@ -250,7 +250,7 @@ public class WasmClassGenerator {
         int flags = 0;
 
         VirtualTable vtable = vtableProvider.lookup(name);
-        int vtableSize = vtable != null ? vtable.getEntries().size() : 0;
+        int vtableSize = vtable != null ? vtable.size() : 0;
 
         DataType arrayType = new DataArray(DataPrimitives.INT, vtableSize);
         DataValue wrapper = new DataStructure((byte) 0, classStructure, arrayType).createValue();
@@ -376,19 +376,28 @@ public class WasmClassGenerator {
 
     private void fillVirtualTable(VirtualTable vtable, DataValue array) {
         int index = 0;
-        for (VirtualTableEntry vtableEntry : vtable.getEntries().values()) {
-            int methodIndex;
-            if (vtableEntry.getImplementor() == null) {
-                methodIndex = -1;
-            } else {
-                methodIndex = functions.computeIfAbsent(vtableEntry.getImplementor(), implementor -> {
-                    int result = functionTable.size();
-                    functionTable.add(names.forMethod(implementor));
-                    return result;
-                });
-            }
+        List<VirtualTable> tables = new ArrayList<>();
+        while (vtable != null) {
+            tables.add(vtable);
+            vtable = vtable.getParent();
+        }
+        for (int i = tables.size() - 1; i >= 0; --i) {
+            vtable = tables.get(i);
+            for (MethodDescriptor method : vtable.getMethods()) {
+                int methodIndex = -1;
+                if (method != null) {
+                    VirtualTableEntry entry = vtable.getEntry(method);
+                    if (entry != null) {
+                        methodIndex = functions.computeIfAbsent(entry.getImplementor(), implementor -> {
+                            int result = functionTable.size();
+                            functionTable.add(names.forMethod(implementor));
+                            return result;
+                        });
+                    }
+                }
 
-            array.setInt(index++, methodIndex);
+                array.setInt(index++, methodIndex);
+            }
         }
     }
 
diff --git a/core/src/main/java/org/teavm/dependency/AbstractInstructionAnalyzer.java b/core/src/main/java/org/teavm/dependency/AbstractInstructionAnalyzer.java
index 51153b943..8df10e176 100644
--- a/core/src/main/java/org/teavm/dependency/AbstractInstructionAnalyzer.java
+++ b/core/src/main/java/org/teavm/dependency/AbstractInstructionAnalyzer.java
@@ -160,7 +160,7 @@ abstract class AbstractInstructionAnalyzer extends AbstractInstructionReader {
                 fieldDep.getValue().connect(receiverNode);
             }
         }
-        initClass(field.getClassName());
+        touchField(instance, fieldDep, field);
     }
 
     @Override
@@ -174,7 +174,17 @@ abstract class AbstractInstructionAnalyzer extends AbstractInstructionReader {
                 valueNode.connect(fieldDep.getValue());
             }
         }
-        initClass(field.getClassName());
+        touchField(instance, fieldDep, field);
+    }
+
+    private void touchField(VariableReader instance, FieldDependency fieldDep, FieldReference field) {
+        if (instance == null) {
+            if (fieldDep.getField() != null) {
+                initClass(fieldDep.getField().getOwnerName());
+            }
+        } else {
+            getAnalyzer().linkClass(field.getClassName());
+        }
     }
 
     @Override
diff --git a/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java b/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java
index 00f5f910e..606232f66 100644
--- a/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java
+++ b/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java
@@ -78,11 +78,11 @@ public class FastDependencyAnalyzer extends DependencyAnalyzer {
         }
 
         if (method.hasModifier(ElementModifier.SYNCHRONIZED)) {
-            processAsyncMethod(methodDep);
+            processAsyncMethod();
         }
     }
 
-    private void processAsyncMethod(MethodDependency methodDep) {
+    private void processAsyncMethod() {
         if (asyncSupported) {
             linkMethod(MONITOR_ENTER_METHOD).use();
         }
@@ -144,7 +144,7 @@ public class FastDependencyAnalyzer extends DependencyAnalyzer {
                     if (fullType instanceof ValueType.Object) {
                         String prefix = key.substring(0, degree) + "L";
                         String className = ((ValueType.Object) fullType).getClassName();
-                        ClassReader cls = getClassSource().get(key);
+                        ClassReader cls = getClassSource().get(className);
                         if (cls != null) {
                             if (cls.getParent() != null) {
                                 node.connect(getSubtypeNode(prefix + cls.getParent().replace('.', '/') + ";"));
diff --git a/core/src/main/java/org/teavm/dependency/Linker.java b/core/src/main/java/org/teavm/dependency/Linker.java
index e3a37ec35..9aab7d06a 100644
--- a/core/src/main/java/org/teavm/dependency/Linker.java
+++ b/core/src/main/java/org/teavm/dependency/Linker.java
@@ -15,6 +15,7 @@
  */
 package org.teavm.dependency;
 
+import org.teavm.model.AccessLevel;
 import org.teavm.model.BasicBlock;
 import org.teavm.model.ClassHolder;
 import org.teavm.model.ClassReader;
@@ -24,6 +25,7 @@ import org.teavm.model.FieldReference;
 import org.teavm.model.Instruction;
 import org.teavm.model.MethodDescriptor;
 import org.teavm.model.MethodHolder;
+import org.teavm.model.MethodReader;
 import org.teavm.model.MethodReference;
 import org.teavm.model.Program;
 import org.teavm.model.instructions.GetFieldInstruction;
@@ -67,11 +69,37 @@ public class Linker {
             for (Instruction insn : block) {
                 if (insn instanceof InvokeInstruction) {
                     InvokeInstruction invoke = (InvokeInstruction) insn;
+                    MethodReference calledRef = invoke.getMethod();
                     if (invoke.getType() == InvocationType.SPECIAL) {
-                        MethodDependencyInfo linkedMethod = dependency.getMethodImplementation(invoke.getMethod());
+                        MethodDependencyInfo linkedMethod = dependency.getMethodImplementation(calledRef);
                         if (linkedMethod != null) {
                             invoke.setMethod(linkedMethod.getReference());
                         }
+                    } else if (invoke.getType() == InvocationType.VIRTUAL) {
+                        MethodDependencyInfo linkedMethod = dependency.getMethodImplementation(calledRef);
+                        if (linkedMethod == null || linkedMethod.isMissing()) {
+                            continue;
+                        }
+                        calledRef = linkedMethod.getReference();
+                        ClassReader cls = dependency.getClassSource().get(calledRef.getClassName());
+                        boolean isFinal = false;
+                        if (cls != null) {
+                            if (cls.hasModifier(ElementModifier.FINAL)) {
+                                isFinal = true;
+                            } else {
+                                MethodReader calledMethod = cls.getMethod(calledRef.getDescriptor());
+                                if (calledMethod != null) {
+                                    if (calledMethod.hasModifier(ElementModifier.FINAL)
+                                            || calledMethod.getLevel() == AccessLevel.PRIVATE) {
+                                        isFinal = true;
+                                    }
+                                }
+                            }
+                        }
+                        if (isFinal) {
+                            invoke.setType(InvocationType.SPECIAL);
+                            invoke.setMethod(calledRef);
+                        }
                     }
                 } else if (insn instanceof GetFieldInstruction) {
                     GetFieldInstruction getField = (GetFieldInstruction) insn;
diff --git a/core/src/main/java/org/teavm/model/classes/InterfaceToClassMapping.java b/core/src/main/java/org/teavm/model/classes/InterfaceToClassMapping.java
deleted file mode 100644
index bf052dbca..000000000
--- a/core/src/main/java/org/teavm/model/classes/InterfaceToClassMapping.java
+++ /dev/null
@@ -1,106 +0,0 @@
-/*
- *  Copyright 2016 Alexey Andreev.
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *       http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- */
-package org.teavm.model.classes;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import org.teavm.model.ClassReader;
-import org.teavm.model.ClassReaderSource;
-import org.teavm.model.ElementModifier;
-import org.teavm.model.ListableClassReaderSource;
-
-public class InterfaceToClassMapping {
-    private Map<String, String> map = new HashMap<>();
-
-    public InterfaceToClassMapping(ListableClassReaderSource classSource) {
-        for (String className : classSource.getClassNames()) {
-            ClassReader cls = classSource.get(className);
-            if (cls.hasModifier(ElementModifier.INTERFACE)) {
-                continue;
-            }
-
-            map.put(className, className);
-            for (String iface : getInterfaces(classSource, className)) {
-                String existing = map.get(iface);
-                if (existing == null) {
-                    map.put(iface, className);
-                } else {
-                    map.put(iface, commonSuperClass(classSource, className, existing));
-                }
-            }
-        }
-    }
-
-    private static Set<String> getInterfaces(ClassReaderSource classSource, String className) {
-        Set<String> interfaces = new HashSet<>();
-        getInterfaces(classSource, className, interfaces);
-        return interfaces;
-    }
-
-    private static void getInterfaces(ClassReaderSource classSource, String className, Set<String> interfaces) {
-        if (!interfaces.add(className)) {
-            return;
-        }
-        ClassReader cls = classSource.get(className);
-        if (cls == null) {
-            return;
-        }
-        for (String iface : cls.getInterfaces()) {
-            getInterfaces(classSource, iface, interfaces);
-        }
-    }
-
-    private static String commonSuperClass(ClassReaderSource classSource, String a, String b) {
-        if (a.equals(b)) {
-            return a;
-        }
-
-        List<String> firstPath = pathToRoot(classSource, a);
-        List<String> secondPath = pathToRoot(classSource, b);
-        Collections.reverse(firstPath);
-        Collections.reverse(secondPath);
-        int min = Math.min(firstPath.size(), secondPath.size());
-        for (int i = 1; i < min; ++i) {
-            if (!firstPath.get(i).equals(secondPath.get(i))) {
-                return firstPath.get(i - 1);
-            }
-        }
-
-        return firstPath.get(0);
-    }
-
-    private static List<String> pathToRoot(ClassReaderSource classSource, String className) {
-        List<String> path = new ArrayList<>();
-        while (true) {
-            path.add(className);
-            ClassReader cls = classSource.get(className);
-            if (cls == null || cls.getParent() == null) {
-                break;
-            }
-            className = cls.getParent();
-        }
-        return path;
-    }
-
-    public String mapClass(String className) {
-        return map.get(className);
-    }
-}
diff --git a/core/src/main/java/org/teavm/model/classes/VirtualTable.java b/core/src/main/java/org/teavm/model/classes/VirtualTable.java
index 42e2965db..5d222dbab 100644
--- a/core/src/main/java/org/teavm/model/classes/VirtualTable.java
+++ b/core/src/main/java/org/teavm/model/classes/VirtualTable.java
@@ -15,28 +15,59 @@
  */
 package org.teavm.model.classes;
 
-import java.util.Collections;
-import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import org.teavm.model.MethodDescriptor;
 
 public class VirtualTable {
     private String className;
-    Map<MethodDescriptor, VirtualTableEntry> entries = new LinkedHashMap<>();
-    private Map<MethodDescriptor, VirtualTableEntry> readonlyEntries;
+    private VirtualTable parent;
+    private List<? extends MethodDescriptor> methods;
+    private Set<MethodDescriptor> methodSet;
+    private Map<MethodDescriptor, VirtualTableEntry> entryMap;
 
-    VirtualTable(String className) {
+    VirtualTable(String className, VirtualTable parent, List<? extends MethodDescriptor> methods,
+            Set<MethodDescriptor> methodSet, Map<MethodDescriptor, VirtualTableEntry> entryMap) {
         this.className = className;
+        this.parent = parent;
+        this.methods = methods;
+        this.methodSet = methodSet;
+        this.entryMap = entryMap;
     }
 
     public String getClassName() {
         return className;
     }
 
-    public Map<MethodDescriptor, VirtualTableEntry> getEntries() {
-        if (readonlyEntries == null) {
-            readonlyEntries = Collections.unmodifiableMap(entries);
+    public VirtualTable getParent() {
+        return parent;
+    }
+
+    public List<? extends MethodDescriptor> getMethods() {
+        return methods;
+    }
+
+    public VirtualTableEntry getEntry(MethodDescriptor method) {
+        return entryMap.get(method);
+    }
+
+    public boolean hasMethod(MethodDescriptor method) {
+        return methodSet.contains(method);
+    }
+
+    public VirtualTable findMethodContainer(MethodDescriptor method) {
+        VirtualTable vt = this;
+        while (vt != null) {
+            if (vt.hasMethod(method)) {
+                return vt;
+            }
+            vt = vt.getParent();
         }
-        return readonlyEntries;
+        return null;
+    }
+
+    public int size() {
+        return methods.size() + (parent != null ? parent.size() : 0);
     }
 }
diff --git a/core/src/main/java/org/teavm/model/classes/VirtualTableBuilder.java b/core/src/main/java/org/teavm/model/classes/VirtualTableBuilder.java
new file mode 100644
index 000000000..984dddbd3
--- /dev/null
+++ b/core/src/main/java/org/teavm/model/classes/VirtualTableBuilder.java
@@ -0,0 +1,440 @@
+/*
+ *  Copyright 2019 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model.classes;
+
+import com.carrotsearch.hppc.ObjectIntHashMap;
+import com.carrotsearch.hppc.ObjectIntMap;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Predicate;
+import org.teavm.common.LCATree;
+import org.teavm.model.AccessLevel;
+import org.teavm.model.ClassReader;
+import org.teavm.model.ElementModifier;
+import org.teavm.model.ListableClassReaderSource;
+import org.teavm.model.MethodDescriptor;
+import org.teavm.model.MethodReader;
+import org.teavm.model.MethodReference;
+
+public class VirtualTableBuilder {
+    private ListableClassReaderSource classes;
+    private Map<String, List<MethodDescriptor>> methodsUsedAtCallSites = new HashMap<>();
+    private Predicate<MethodReference> methodCalledVirtually = m -> true;
+    private Map<String, TableBuilder> tables;
+    private Map<String, List<String>> classChildren;
+    private LCATree classTree;
+    private ObjectIntMap<String> classTreeIndexes;
+    private List<String> classList;
+    private VirtualTableProvider result;
+
+    public VirtualTableBuilder(ListableClassReaderSource classes) {
+        this.classes = classes;
+    }
+
+    public void setMethodsUsedAtCallSites(Collection<? extends MethodReference> methodsUsedAtCallSites) {
+        for (MethodReference method : methodsUsedAtCallSites) {
+            this.methodsUsedAtCallSites.computeIfAbsent(method.getClassName(), k -> new ArrayList<>())
+                    .add(method.getDescriptor());
+        }
+    }
+
+    public void setMethodCalledVirtually(Predicate<MethodReference> methodCalledVirtually) {
+        this.methodCalledVirtually = methodCalledVirtually;
+    }
+
+    public VirtualTableProvider build() {
+        tables = new HashMap<>();
+
+        buildVirtualTables();
+        cleanupVirtualTables();
+
+        classChildren = new HashMap<>();
+        buildClassChildren();
+        liftEntries();
+
+        buildResult();
+        tables = null;
+        return result;
+    }
+
+    private void buildVirtualTables() {
+        for (String className : classes.getClassNames()) {
+            fillClass(className);
+        }
+    }
+
+    private void fillClass(String className) {
+        ClassReader cls = classes.get(className);
+        if (cls == null) {
+            return;
+        }
+        if (tables.containsKey(className)) {
+            return;
+        }
+
+        TableBuilder table = new TableBuilder();
+        tables.put(className, table);
+
+        String parent = cls.getParent();
+        if (parent != null) {
+            fillClass(parent);
+            TableBuilder parentTable = tables.get(parent);
+            if (parentTable != null) {
+                copyEntries(parentTable, table);
+            }
+        }
+
+        for (String itf : cls.getInterfaces()) {
+            fillClass(itf);
+            TableBuilder itfTable = tables.get(itf);
+            if (itfTable != null) {
+                copyEntries(itfTable, table);
+            }
+        }
+
+        List<MethodDescriptor> methodsAtCallSites = methodsUsedAtCallSites.get(className);
+        if (methodsAtCallSites != null) {
+            for (MethodDescriptor methodDesc : methodsAtCallSites) {
+                MethodReader method = cls.getMethod(methodDesc);
+                if (method != null) {
+                    if (method.hasModifier(ElementModifier.FINAL)
+                            || method.getLevel() == AccessLevel.PRIVATE
+                            || cls.hasModifier(ElementModifier.FINAL)) {
+                        continue;
+                    }
+                }
+                table.entries.computeIfAbsent(methodDesc, k -> new EntryBuilder());
+            }
+        }
+
+        for (MethodReader method : cls.getMethods()) {
+            if (method.hasModifier(ElementModifier.ABSTRACT)
+                    || method.hasModifier(ElementModifier.STATIC)
+                    || method.getName().equals("<init>")
+                    || method.getLevel() == AccessLevel.PRIVATE) {
+                continue;
+            }
+
+            EntryBuilder entry = table.entries.get(method.getDescriptor());
+            if (entry == null) {
+                if (method.hasModifier(ElementModifier.FINAL)
+                        || method.getLevel() == AccessLevel.PRIVATE
+                        || cls.hasModifier(ElementModifier.FINAL)) {
+                    continue;
+                }
+                entry = new EntryBuilder();
+                table.entries.put(method.getDescriptor(), entry);
+            }
+            entry.implementor = method.getReference();
+        }
+    }
+
+    private void copyEntries(TableBuilder source, TableBuilder target) {
+        for (Map.Entry<MethodDescriptor, EntryBuilder> entry : source.entries.entrySet()) {
+            EntryBuilder targetEntry = target.entries.computeIfAbsent(entry.getKey(), k -> new EntryBuilder());
+            targetEntry.addParent(entry.getValue());
+            if (entry.getValue().implementor != null && targetEntry.implementor == null) {
+                targetEntry.implementor = entry.getValue().implementor;
+            }
+        }
+    }
+
+    private void cleanupVirtualTables() {
+        for (String className : classes.getClassNames()) {
+            TableBuilder table = tables.get(className);
+            for (MethodDescriptor method : table.entries.keySet().toArray(new MethodDescriptor[0])) {
+                EntryBuilder entry = table.entries.get(method);
+                if (entry.implementor != null && !methodCalledVirtually.test(entry.implementor)) {
+                    entry.implementor = null;
+                }
+            }
+        }
+    }
+
+    private void buildClassChildren() {
+        for (String className : classes.getClassNames()) {
+            ClassReader cls = classes.get(className);
+            if (cls.hasModifier(ElementModifier.INTERFACE)) {
+                continue;
+            }
+            if (cls.getParent() != null) {
+                classChildren.computeIfAbsent(cls.getParent(), c -> new ArrayList<>()).add(className);
+            }
+        }
+    }
+
+    private void liftEntries() {
+        buildClassTree();
+        for (Map.Entry<MethodDescriptor, List<String>> group : groupMethods().entrySet()) {
+            String commonSuperclass = commonSuperclass(group.getValue());
+            Set<String> visited = new HashSet<>();
+            for (String cls : group.getValue()) {
+                liftEntriesAtTable(cls, commonSuperclass, group.getKey(), visited);
+            }
+        }
+        classTree = null;
+        classTreeIndexes = null;
+        classList = null;
+    }
+
+    private void buildClassTree() {
+        classTree = new LCATree(classes.getClassNames().size());
+        classTreeIndexes = new ObjectIntHashMap<>();
+        classList = new ArrayList<>();
+        classList.add(null);
+        for (String className : classes.getClassNames()) {
+            ClassReader cls = classes.get(className);
+            if (cls.hasModifier(ElementModifier.INTERFACE)) {
+                continue;
+            }
+            insertClassToTree(className);
+        }
+    }
+
+    private int insertClassToTree(String className) {
+        int index = classTreeIndexes.getOrDefault(className, 0);
+        if (index == 0) {
+            ClassReader cls = classes.get(className);
+            int parent = cls != null && cls.getParent() != null ? insertClassToTree(cls.getParent()) : 0;
+            index = classTree.addNode(parent);
+            classList.add(className);
+            classTreeIndexes.put(className, index);
+        }
+        return index;
+    }
+
+    private String commonSuperclass(List<String> classNames) {
+        int result = classTreeIndexes.get(classNames.get(0));
+        for (int i = 1; i < classNames.size(); ++i) {
+            int next = classTreeIndexes.get(classNames.get(i));
+            result = classTree.lcaOf(result, next);
+        }
+        return classList.get(result);
+    }
+
+    private Map<MethodDescriptor, List<String>> groupMethods() {
+        Map<MethodDescriptor, List<String>> groups = new LinkedHashMap<>();
+        for (String className : classes.getClassNames()) {
+            ClassReader cls = classes.get(className);
+            if (cls.hasModifier(ElementModifier.INTERFACE)) {
+                continue;
+            }
+
+            TableBuilder table = tables.get(className);
+            TableBuilder parentTable = cls.getParent() != null ? tables.get(cls.getParent()) : null;
+            for (MethodDescriptor method : table.entries.keySet()) {
+                EntryBuilder entry = table.entries.get(method);
+                if (entry.implementor == null) {
+                    continue;
+                }
+                if (parentTable != null) {
+                    EntryBuilder parentEntry = parentTable.entries.get(method);
+                    if (parentEntry != null && entry.implementor.equals(parentEntry.implementor)) {
+                        continue;
+                    }
+                }
+
+                groups.computeIfAbsent(method, k -> new ArrayList<>()).add(className);
+            }
+        }
+
+        groups.entrySet().removeIf(entry -> entry.getValue().size() == 1);
+        return groups;
+    }
+
+    private void liftEntriesAtTable(String className, String toClass, MethodDescriptor method,
+            Set<String> visited) {
+        while (visited.add(className)) {
+            TableBuilder table = tables.get(className);
+            EntryBuilder entry = table.entries.get(method);
+            if (entry == null) {
+                table.entries.put(method, new EntryBuilder());
+            }
+
+            if (className.equals(toClass)) {
+                break;
+            }
+            ClassReader cls = classes.get(className);
+            if (cls == null) {
+                break;
+            }
+            className = cls.getParent();
+        }
+    }
+
+    private void buildResult() {
+        result = new VirtualTableProvider();
+        buildResultForClasses();
+        buildResultForInterfaces();
+    }
+
+    private void buildResultForClasses() {
+        for (String className : classes.getClassNames()) {
+            ClassReader cls = classes.get(className);
+            if (cls.hasModifier(ElementModifier.INTERFACE) || cls.getParent() != null) {
+                continue;
+            }
+
+            buildResultForClass(className, new Context(), null);
+        }
+    }
+
+    private void buildResultForClass(String className, Context context, VirtualTable parent) {
+        TableBuilder table = tables.get(className);
+        ClassReader cls = classes.get(className);
+
+        int start = context.methods.size();
+        Map<MethodDescriptor, VirtualTableEntry> resultEntries = new HashMap<>();
+        for (MethodDescriptor method : table.entries.keySet()) {
+            EntryBuilder entry = table.entries.get(method);
+            int index = context.indexes.getOrDefault(method, -1);
+            if (index < 0) {
+                index = context.indexes.size();
+                context.indexes.put(method, index);
+                context.methods.add(method);
+            }
+
+            if (entry.implementor != null) {
+                VirtualTableEntry resultEntry = new VirtualTableEntry(method, entry.implementor, index);
+                resultEntries.put(method, resultEntry);
+
+                propagateInterfaceIndexes(cls, method, index);
+            }
+        }
+
+        List<MethodDescriptor> newMethods = context.methods.subList(start, context.methods.size());
+        List<? extends MethodDescriptor> readonlyNewMethods = Collections.unmodifiableList(
+                Arrays.asList(newMethods.toArray(new MethodDescriptor[0])));
+        VirtualTable resultTable = new VirtualTable(className, parent, readonlyNewMethods,
+                new HashSet<>(readonlyNewMethods), resultEntries);
+        result.virtualTables.put(className, resultTable);
+
+        List<String> children = classChildren.get(className);
+        if (children != null) {
+            for (String child : children) {
+                buildResultForClass(child, context, resultTable);
+            }
+        }
+
+        newMethods = context.methods.subList(start, context.methods.size());
+        for (MethodDescriptor method : newMethods) {
+            context.indexes.remove(method);
+        }
+        newMethods.clear();
+    }
+
+    private void propagateInterfaceIndexes(ClassReader cls, MethodDescriptor method, int index) {
+        while (true) {
+            for (String itf : cls.getInterfaces()) {
+                TableBuilder itfTable = tables.get(itf);
+                if (itfTable != null) {
+                    EntryBuilder itfEntry = itfTable.entries.get(method);
+                    if (itfEntry != null) {
+                        propagateInterfaceIndex(itfEntry, index);
+                    }
+                }
+            }
+
+            if (cls.getParent() == null) {
+                break;
+            }
+            cls = classes.get(cls.getParent());
+            if (cls == null) {
+                break;
+            }
+
+            TableBuilder table = tables.get(cls.getName());
+            EntryBuilder entry = table.entries.get(method);
+            if (entry == null || entry.implementor != null) {
+                break;
+            }
+        }
+    }
+
+    private void propagateInterfaceIndex(EntryBuilder entry, int index) {
+        if (entry.index >= 0) {
+            return;
+        }
+        entry.index = index;
+        if (entry.parents != null) {
+            for (EntryBuilder parent : entry.parents) {
+                propagateInterfaceIndex(parent, index);
+            }
+        }
+    }
+
+    private void buildResultForInterfaces() {
+        for (String className : classes.getClassNames()) {
+            ClassReader cls = classes.get(className);
+            if (!cls.hasModifier(ElementModifier.INTERFACE)) {
+                continue;
+            }
+
+            List<MethodDescriptor> methods = new ArrayList<>();
+            Set<MethodDescriptor> methodSet = new HashSet<>();
+            TableBuilder table = tables.get(className);
+            for (MethodDescriptor method : table.entries.keySet()) {
+                EntryBuilder entry = table.entries.get(method);
+                if (entry.index < 0) {
+                    continue;
+                }
+                if (entry.index >= methods.size()) {
+                    methods.addAll(Collections.nCopies(entry.index - methods.size() + 1, null));
+                }
+                methods.set(entry.index, method);
+                methodSet.add(method);
+            }
+
+            List<? extends MethodDescriptor> readonlyNewMethods = Collections.unmodifiableList(
+                    Arrays.asList(methods.toArray(new MethodDescriptor[0])));
+            VirtualTable resultTable = new VirtualTable(className, null, readonlyNewMethods,
+                    methodSet, Collections.emptyMap());
+            result.virtualTables.put(className, resultTable);
+        }
+    }
+
+    static class TableBuilder {
+        Map<MethodDescriptor, EntryBuilder> entries = new LinkedHashMap<>();
+    }
+
+    static class EntryBuilder {
+        MethodReference implementor;
+        EntryBuilder[] parents;
+        int index = -1;
+
+        void addParent(EntryBuilder parent) {
+            if (parents == null) {
+                parents = new EntryBuilder[] { parent };
+            } else {
+                parents = Arrays.copyOf(parents, parents.length + 1);
+                parents[parents.length - 1] = parent;
+            }
+        }
+    }
+
+    static class Context {
+        ObjectIntMap<MethodDescriptor> indexes = new ObjectIntHashMap<>();
+        List<MethodDescriptor> methods = new ArrayList<>();
+    }
+}
diff --git a/core/src/main/java/org/teavm/model/classes/VirtualTableEntry.java b/core/src/main/java/org/teavm/model/classes/VirtualTableEntry.java
index 92370304e..e10d3973f 100644
--- a/core/src/main/java/org/teavm/model/classes/VirtualTableEntry.java
+++ b/core/src/main/java/org/teavm/model/classes/VirtualTableEntry.java
@@ -19,22 +19,16 @@ import org.teavm.model.MethodDescriptor;
 import org.teavm.model.MethodReference;
 
 public class VirtualTableEntry {
-    private VirtualTable virtualTable;
     private MethodDescriptor method;
     MethodReference implementor;
     private int index;
 
-    VirtualTableEntry(VirtualTable virtualTable, MethodDescriptor method, MethodReference implementor, int index) {
-        this.virtualTable = virtualTable;
+    VirtualTableEntry(MethodDescriptor method, MethodReference implementor, int index) {
         this.method = method;
         this.implementor = implementor;
         this.index = index;
     }
 
-    public VirtualTable getVirtualTable() {
-        return virtualTable;
-    }
-
     public MethodDescriptor getMethod() {
         return method;
     }
diff --git a/core/src/main/java/org/teavm/model/classes/VirtualTableProvider.java b/core/src/main/java/org/teavm/model/classes/VirtualTableProvider.java
index 3ad46e034..fe42b57e2 100644
--- a/core/src/main/java/org/teavm/model/classes/VirtualTableProvider.java
+++ b/core/src/main/java/org/teavm/model/classes/VirtualTableProvider.java
@@ -15,116 +15,25 @@
  */
 package org.teavm.model.classes;
 
-import java.util.HashMap;
-import java.util.HashSet;
 import java.util.LinkedHashMap;
-import java.util.LinkedHashSet;
 import java.util.Map;
-import java.util.Set;
-import java.util.function.Predicate;
-import org.teavm.model.ClassReader;
-import org.teavm.model.ClassReaderSource;
-import org.teavm.model.ElementModifier;
-import org.teavm.model.ListableClassReaderSource;
-import org.teavm.model.MethodDescriptor;
-import org.teavm.model.MethodReader;
 import org.teavm.model.MethodReference;
 
 public class VirtualTableProvider {
-    private ClassReaderSource classSource;
-    private Map<String, Set<MethodDescriptor>> virtualMethodMap = new HashMap<>();
-    private Map<String, VirtualTable> virtualTables = new LinkedHashMap<>();
-    private InterfaceToClassMapping interfaceMapping;
+    Map<String, VirtualTable> virtualTables = new LinkedHashMap<>();
 
-    public VirtualTableProvider(ListableClassReaderSource classSource, Set<MethodReference> virtualMethods,
-            Predicate<MethodReference> methodCalledVirtually) {
-        this.classSource = classSource;
-        interfaceMapping = new InterfaceToClassMapping(classSource);
-
-        Set<String> classNames = new HashSet<>(classSource.getClassNames());
-        for (MethodReference virtualMethod : virtualMethods) {
-            String cls = interfaceMapping.mapClass(virtualMethod.getClassName());
-            if (cls == null) {
-                cls = virtualMethod.getClassName();
-            }
-            classNames.add(cls);
-            virtualMethodMap.computeIfAbsent(cls, c -> new LinkedHashSet<>()).add(virtualMethod.getDescriptor());
-        }
-
-        for (String className : classNames) {
-            fillClass(className, methodCalledVirtually);
-        }
-    }
-
-    private void fillClass(String className, Predicate<MethodReference> methodCalledVirtually) {
-        if (virtualTables.containsKey(className)) {
-            return;
-        }
-
-        VirtualTable table = new VirtualTable(className);
-        virtualTables.put(className, table);
-        ClassReader cls = classSource.get(className);
-        if (cls == null) {
-            return;
-        }
-        if (cls.getParent() != null) {
-            fillClass(cls.getParent(), methodCalledVirtually);
-            copyEntriesFromSupertype(table, virtualTables.get(cls.getParent()));
-        }
-        for (String itf : cls.getInterfaces()) {
-            fillClass(itf, methodCalledVirtually);
-            copyEntriesFromSupertype(table, virtualTables.get(itf));
-        }
-
-        Set<MethodDescriptor> newDescriptors = virtualMethodMap.get(className);
-        if (newDescriptors != null) {
-            for (MethodDescriptor method : newDescriptors) {
-                if (!table.entries.containsKey(method)) {
-                    MethodReader implementation = classSource.resolveImplementation(
-                            className, method);
-                    MethodReference implementationRef = implementation != null
-                            ? implementation.getReference()
-                            : null;
-                    if (implementationRef != null && !methodCalledVirtually.test(implementationRef)) {
-                        implementationRef = null;
-                    }
-                    table.entries.put(method, new VirtualTableEntry(table, method, implementationRef,
-                            table.entries.size()));
-                }
-            }
-        }
-
-        for (MethodReader method : cls.getMethods()) {
-            if (method.hasModifier(ElementModifier.ABSTRACT)) {
-                continue;
-            }
-            VirtualTableEntry entry = table.entries.get(method.getDescriptor());
-            if (entry != null && methodCalledVirtually.test(method.getReference())) {
-                entry.implementor = method.getReference();
-            }
-        }
-    }
-
-    private void copyEntriesFromSupertype(VirtualTable table, VirtualTable supertypeTable) {
-        for (VirtualTableEntry parentEntry : supertypeTable.entries.values()) {
-            VirtualTableEntry existingEntry = table.entries.get(parentEntry.getMethod());
-            if (existingEntry == null || existingEntry.getImplementor() == null) {
-                VirtualTableEntry entry = new VirtualTableEntry(table, parentEntry.getMethod(),
-                        parentEntry.getImplementor(), parentEntry.getIndex());
-                table.entries.put(entry.getMethod(), entry);
-            }
-        }
+    VirtualTableProvider() {
     }
 
     public VirtualTableEntry lookup(MethodReference method) {
-        VirtualTable vtable = virtualTables.get(interfaceMapping.mapClass(method.getClassName()));
+        VirtualTable vtable = virtualTables.get(method.getClassName());
         if (vtable == null) {
             return null;
         }
-        return vtable.getEntries().get(method.getDescriptor());
+        return vtable.getEntry(method.getDescriptor());
     }
 
     public VirtualTable lookup(String className) {
-        return virtualTables.get(interfaceMapping.mapClass(className));
+        return virtualTables.get(className);
     }
 }
diff --git a/core/src/main/java/org/teavm/vm/TeaVM.java b/core/src/main/java/org/teavm/vm/TeaVM.java
index 27ae7e75b..afad5a10a 100644
--- a/core/src/main/java/org/teavm/vm/TeaVM.java
+++ b/core/src/main/java/org/teavm/vm/TeaVM.java
@@ -908,6 +908,11 @@ public class TeaVM implements TeaVMHost, ServiceRepository {
         public ClassInitializerInfo getClassInitializerInfo() {
             return classInitializerInfo;
         }
+
+        @Override
+        public TeaVMOptimizationLevel getOptimizationLevel() {
+            return optimizationLevel;
+        }
     };
 
     class PostProcessingClassHolderSource implements ListableClassHolderSource {
@@ -954,12 +959,14 @@ public class TeaVM implements TeaVMHost, ServiceRepository {
                     }
                     return program;
                 };
+
                 for (MethodHolder method : cls.getMethods().toArray(new MethodHolder[0])) {
                     MethodDependencyInfo methodDep = dependencyAnalyzer.getMethod(method.getReference());
                     if (methodDep == null) {
                         cls.removeMethod(method);
                     } else if (!methodDep.isUsed()) {
                         method.getModifiers().add(ElementModifier.ABSTRACT);
+                        method.setProgram(null);
                     } else {
                         MethodReader methodReader = classReader.getMethod(method.getDescriptor());
                         if (methodReader != null && methodReader.getProgram() != null) {
diff --git a/core/src/main/java/org/teavm/vm/TeaVMTargetController.java b/core/src/main/java/org/teavm/vm/TeaVMTargetController.java
index 757d124da..9306abf57 100644
--- a/core/src/main/java/org/teavm/vm/TeaVMTargetController.java
+++ b/core/src/main/java/org/teavm/vm/TeaVMTargetController.java
@@ -44,6 +44,8 @@ public interface TeaVMTargetController {
 
     ServiceRepository getServices();
 
+    TeaVMOptimizationLevel getOptimizationLevel();
+
     boolean isFriendlyToDebugger();
 
     Map<? extends String, ? extends TeaVMEntryPoint> getEntryPoints();
diff --git a/core/src/main/resources/org/teavm/backend/c/date.c b/core/src/main/resources/org/teavm/backend/c/date.c
index 5d1029a0c..ca8d32f05 100644
--- a/core/src/main/resources/org/teavm/backend/c/date.c
+++ b/core/src/main/resources/org/teavm/backend/c/date.c
@@ -1,8 +1,16 @@
 #include "runtime.h"
 
+#ifndef _XOPEN_SOURCE
 #define _XOPEN_SOURCE
+#endif
+
+#ifndef __USE_XOPEN
 #define __USE_XOPEN
+#endif
+
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 
 #include <time.h>
 
diff --git a/tests/compile-c-unix-fast.sh b/tests/compile-c-unix-fast.sh
new file mode 100755
index 000000000..9d2dbeeea
--- /dev/null
+++ b/tests/compile-c-unix-fast.sh
@@ -0,0 +1,2 @@
+SOURCE_DIR=$(pwd)
+gcc -g -O0 -lrt -lm all.c -o run_test
\ No newline at end of file
diff --git a/tools/cli/pom.xml b/tools/cli/pom.xml
index 95a56514e..5fda44b4c 100644
--- a/tools/cli/pom.xml
+++ b/tools/cli/pom.xml
@@ -45,6 +45,12 @@
       <version>${project.version}</version>
       <scope>runtime</scope>
     </dependency>
+    <dependency>
+      <groupId>org.teavm</groupId>
+      <artifactId>teavm-metaprogramming-api</artifactId>
+      <version>${project.version}</version>
+      <scope>runtime</scope>
+    </dependency>
     <dependency>
       <groupId>org.teavm</groupId>
       <artifactId>teavm-metaprogramming-impl</artifactId>
@@ -125,6 +131,13 @@
               <goal>shade</goal>
             </goals>
             <configuration>
+              <artifactSet>
+                <excludes>
+                  <exclude>junit:junit</exclude>
+                  <exclude>com.fasterxml.jackson.core:jackson-annotations</exclude>
+                  <exclude>org.mozilla:rhino</exclude>
+                </excludes>
+              </artifactSet>
               <transformers>
                 <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
@@ -132,6 +145,18 @@
                 </transformer>
               </transformers>
               <relocations>
+                <relocation>
+                  <pattern>org.objectweb.asm</pattern>
+                  <shadedPattern>org.teavm.asm</shadedPattern>
+                </relocation>
+                <relocation>
+                  <pattern>org.mozilla</pattern>
+                  <shadedPattern>org.teavm.rhino</shadedPattern>
+                </relocation>
+                <relocation>
+                  <pattern>com.carrotsearch.hppc</pattern>
+                  <shadedPattern>org.teavm.hppc</shadedPattern>
+                </relocation>
                 <relocation>
                   <pattern>org.apache.commons</pattern>
                   <shadedPattern>org.teavm.apachecommons</shadedPattern>
diff --git a/tools/cli/src/main/java/org/teavm/cli/TeaVMRunner.java b/tools/cli/src/main/java/org/teavm/cli/TeaVMRunner.java
index 369739061..cb553ded2 100644
--- a/tools/cli/src/main/java/org/teavm/cli/TeaVMRunner.java
+++ b/tools/cli/src/main/java/org/teavm/cli/TeaVMRunner.java
@@ -132,7 +132,7 @@ public final class TeaVMRunner {
                 .withLongOpt("min-heap")
                 .withArgName("size")
                 .hasArg()
-                .withDescription("Minimum heap size in bytes (for C and WebAssembly)")
+                .withDescription("Minimum heap size in megabytes (for C and WebAssembly)")
                 .create());
         options.addOption(OptionBuilder
                 .withLongOpt("max-toplevel-names")
@@ -323,7 +323,7 @@ public final class TeaVMRunner {
                 printUsage();
                 return;
             }
-            tool.setMinHeapSize(size);
+            tool.setMinHeapSize(size * 1024 * 1024);
         }
     }