diff --git a/core/src/main/java/org/teavm/backend/javascript/codegen/DefaultNamingStrategy.java b/core/src/main/java/org/teavm/backend/javascript/codegen/DefaultNamingStrategy.java
index a8d1dd225..e7ea7e108 100644
--- a/core/src/main/java/org/teavm/backend/javascript/codegen/DefaultNamingStrategy.java
+++ b/core/src/main/java/org/teavm/backend/javascript/codegen/DefaultNamingStrategy.java
@@ -17,13 +17,23 @@ package org.teavm.backend.javascript.codegen;
 
 import java.util.HashMap;
 import java.util.Map;
-import org.teavm.model.*;
+import org.teavm.model.AccessLevel;
+import org.teavm.model.ClassReader;
+import org.teavm.model.ClassReaderSource;
+import org.teavm.model.FieldReader;
+import org.teavm.model.FieldReference;
+import org.teavm.model.MethodDescriptor;
+import org.teavm.model.MethodReader;
+import org.teavm.model.MethodReference;
 
 public class DefaultNamingStrategy implements NamingStrategy {
+    private static final byte NO_CLASSIFIER = 0;
+    private static final byte INIT_CLASSIFIER = 1;
+
     private final AliasProvider aliasProvider;
     private final ClassReaderSource classSource;
-    private final Map<String, String> aliases = new HashMap<>();
-    private final Map<String, ScopedName> privateAliases = new HashMap<>();
+    private final Map<MethodDescriptor, String> aliases = new HashMap<>();
+    private final Map<Key, ScopedName> privateAliases = new HashMap<>();
     private final Map<String, ScopedName> classAliases = new HashMap<>();
     private final Map<FieldReference, String> fieldAliases = new HashMap<>();
     private final Map<FieldReference, ScopedName> staticFieldAliases = new HashMap<>();
@@ -43,35 +53,33 @@ public class DefaultNamingStrategy implements NamingStrategy {
 
     @Override
     public String getNameFor(MethodDescriptor method) {
-        String key = method.toString();
-        String alias = aliases.get(key);
+        String alias = aliases.get(method);
         if (alias == null) {
             alias = aliasProvider.getMethodAlias(method);
-            aliases.put(key, alias);
+            aliases.put(method, alias);
         }
         return alias;
     }
 
     @Override
     public ScopedName getFullNameFor(MethodReference method) {
-        return getFullNameFor(method, 'M');
+        return getFullNameFor(method, NO_CLASSIFIER);
     }
 
     @Override
     public ScopedName getNameForInit(MethodReference method) {
-        return getFullNameFor(method, 'I');
+        return getFullNameFor(method, INIT_CLASSIFIER);
     }
 
-    private ScopedName getFullNameFor(MethodReference method, char classifier) {
+    private ScopedName getFullNameFor(MethodReference method, byte classifier) {
         MethodReference originalMethod = method;
         method = getRealMethod(method);
         if (method == null) {
             method = originalMethod;
         }
 
-        MethodReference resolvedMethod = method;
-        return privateAliases.computeIfAbsent(classifier + method.toString(),
-                key -> aliasProvider.getStaticMethodAlias(resolvedMethod));
+        return privateAliases.computeIfAbsent(new Key(classifier, method),
+                key -> aliasProvider.getStaticMethodAlias(key.data));
     }
 
     @Override
@@ -155,4 +163,38 @@ public class DefaultNamingStrategy implements NamingStrategy {
         }
         return fieldRef;
     }
+
+    private final class Key {
+        final MethodReference data;
+        int hash;
+        final byte classifier;
+
+        Key(byte classifier, MethodReference data) {
+            this.classifier = classifier;
+            this.data = data;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (!(o instanceof Key)) {
+                return false;
+            }
+            Key key = (Key) o;
+            return classifier == key.classifier && data.equals(key.data);
+        }
+
+        @Override
+        public int hashCode() {
+            if (hash == 0) {
+                hash = (classifier * 31 + data.hashCode()) * 17;
+                if (hash == 0) {
+                    hash++;
+                }
+            }
+            return hash;
+        }
+    }
 }
diff --git a/core/src/main/java/org/teavm/cache/AstIO.java b/core/src/main/java/org/teavm/cache/AstIO.java
index bd14165fe..036aa3a67 100644
--- a/core/src/main/java/org/teavm/cache/AstIO.java
+++ b/core/src/main/java/org/teavm/cache/AstIO.java
@@ -20,6 +20,7 @@ import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import org.teavm.ast.ArrayType;
 import org.teavm.ast.AssignmentStatement;
@@ -82,16 +83,22 @@ public class AstIO {
     private static final UnaryOperation[] unaryOperations = UnaryOperation.values();
     private final SymbolTable symbolTable;
     private final SymbolTable fileTable;
+    private final SymbolTable variableTable;
     private final Map<String, IdentifiedStatement> statementMap = new HashMap<>();
     private ReferenceCache referenceCache;
+    private TextLocation lastWrittenLocation;
+    private TextLocation lastReadLocation;
 
-    public AstIO(ReferenceCache referenceCache, SymbolTable symbolTable, SymbolTable fileTable) {
+    public AstIO(ReferenceCache referenceCache, SymbolTable symbolTable, SymbolTable fileTable,
+            SymbolTable variableTable) {
         this.referenceCache = referenceCache;
         this.symbolTable = symbolTable;
         this.fileTable = fileTable;
+        this.variableTable = variableTable;
     }
 
     public void write(VarDataOutput output, ControlFlowEntry[] cfg) throws IOException {
+        lastWrittenLocation = null;
         output.writeUnsigned(cfg.length);
         for (ControlFlowEntry entry : cfg) {
             writeLocation(output, entry.from);
@@ -118,10 +125,11 @@ public class AstIO {
     private void write(VarDataOutput output, VariableNode variable) throws IOException {
         output.writeUnsigned(variable.getIndex());
         output.writeUnsigned(variable.getType().ordinal());
-        output.write(variable.getName());
+        output.writeUnsigned(variable.getName() != null ? variableTable.lookup(variable.getName()) + 1 : 0);
     }
 
     public ControlFlowEntry[] readControlFlow(VarDataInput input) throws IOException {
+        lastReadLocation = null;
         int size = input.readUnsigned();
         ControlFlowEntry[] result = new ControlFlowEntry[size];
         for (int i = 0; i < size; ++i) {
@@ -143,6 +151,7 @@ public class AstIO {
         for (int i = 0; i < varCount; ++i) {
             node.getVariables().add(readVariable(input));
         }
+        lastReadLocation = null;
         node.setBody(readStatement(input));
         return node;
     }
@@ -151,7 +160,8 @@ public class AstIO {
         int index = input.readUnsigned();
         VariableType type = VariableType.values()[input.readUnsigned()];
         VariableNode variable = new VariableNode(index, type);
-        variable.setName(input.read());
+        int nameIndex = input.readUnsigned();
+        variable.setName(nameIndex != 0 ? variableTable.at(nameIndex - 1) : null);
         return variable;
     }
 
@@ -162,10 +172,11 @@ public class AstIO {
             write(output, var);
         }
         try {
-             output.writeUnsigned(method.getBody().size());
-             for (int i = 0; i < method.getBody().size(); ++i) {
-                 method.getBody().get(i).getStatement().acceptVisitor(new NodeWriter(output));
-             }
+            output.writeUnsigned(method.getBody().size());
+            NodeWriter writer = new NodeWriter(output);
+            for (int i = 0; i < method.getBody().size(); ++i) {
+                method.getBody().get(i).getStatement().acceptVisitor(writer);
+            }
         } catch (IOExceptionWrapper e) {
             throw new IOException("Error writing method body", e.getCause());
         }
@@ -179,6 +190,7 @@ public class AstIO {
             node.getVariables().add(readVariable(input));
         }
         int partCount = input.readUnsigned();
+        lastReadLocation = null;
         for (int i = 0; i < partCount; ++i) {
             AsyncMethodPart part = new AsyncMethodPart();
             part.setStatement(readStatement(input));
@@ -200,14 +212,21 @@ public class AstIO {
     private void writeLocation(VarDataOutput output, TextLocation location) throws IOException {
         if (location == null || location.getFileName() == null) {
             output.writeUnsigned(0);
+            lastWrittenLocation = null;
+        } else if (lastWrittenLocation != null && lastWrittenLocation.getFileName().equals(location.getFileName())) {
+            output.writeUnsigned(1);
+            output.writeSigned(location.getLine() - lastWrittenLocation.getLine());
+            lastWrittenLocation = location;
         } else {
-            output.writeUnsigned(fileTable.lookup(location.getFileName()) + 1);
+            output.writeUnsigned(fileTable.lookup(location.getFileName()) + 2);
             output.writeUnsigned(location.getLine());
+            lastWrittenLocation = location;
         }
     }
 
     private class NodeWriter implements ExprVisitor, StatementVisitor {
         private final VarDataOutput output;
+        private TextLocation lastLocation;
 
         NodeWriter(VarDataOutput output) {
             super();
@@ -220,7 +239,22 @@ public class AstIO {
         }
 
         private void writeLocation(TextLocation location) throws IOException {
-            AstIO.this.writeLocation(output, location);
+            if (Objects.equals(location, lastLocation)) {
+                return;
+            }
+            if (location == null || location.getFileName() == null) {
+                output.writeUnsigned(127);
+                lastLocation = null;
+            } else if (lastLocation != null && lastLocation.getFileName().equals(location.getFileName())) {
+                output.writeUnsigned(126);
+                output.writeSigned(location.getLine() - lastLocation.getLine());
+                lastLocation = location;
+            } else {
+                output.writeUnsigned(125);
+                output.writeUnsigned(fileTable.lookup(location.getFileName()));
+                output.writeUnsigned(location.getLine());
+                lastLocation = location;
+            }
         }
 
         private void writeSequence(List<Statement> sequence) throws IOException {
@@ -233,8 +267,8 @@ public class AstIO {
         @Override
         public void visit(AssignmentStatement statement) {
             try {
-                output.writeUnsigned(statement.getLeftValue() != null ? 0 : 1);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(statement.getLeftValue() != null ? 0 : 1);
                 if (statement.getLeftValue() != null) {
                     writeExpr(statement.getLeftValue());
                 }
@@ -316,8 +350,8 @@ public class AstIO {
         @Override
         public void visit(BreakStatement statement) {
             try {
-                output.writeUnsigned(statement.getTarget() != null && statement.getTarget().getId() != null ? 8 : 9);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(statement.getTarget() != null && statement.getTarget().getId() != null ? 8 : 9);
                 if (statement.getTarget() != null && statement.getTarget().getId() != null) {
                     output.write(statement.getTarget().getId());
                 }
@@ -329,8 +363,8 @@ public class AstIO {
         @Override
         public void visit(ContinueStatement statement) {
             try {
-                output.writeUnsigned(statement.getTarget() != null && statement.getTarget().getId() != null ? 10 : 11);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(statement.getTarget() != null && statement.getTarget().getId() != null ? 10 : 11);
                 if (statement.getTarget() != null && statement.getTarget().getId() != null) {
                     output.write(statement.getTarget().getId());
                 }
@@ -342,8 +376,8 @@ public class AstIO {
         @Override
         public void visit(ReturnStatement statement) {
             try {
-                output.writeUnsigned(statement.getResult() != null ? 12 : 13);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(statement.getResult() != null ? 12 : 13);
                 if (statement.getResult() != null) {
                     writeExpr(statement.getResult());
                 }
@@ -355,8 +389,8 @@ public class AstIO {
         @Override
         public void visit(ThrowStatement statement) {
             try {
-                output.writeUnsigned(14);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(14);
                 writeExpr(statement.getException());
             } catch (IOException e) {
                 throw new IOExceptionWrapper(e);
@@ -366,8 +400,8 @@ public class AstIO {
         @Override
         public void visit(InitClassStatement statement) {
             try {
-                output.writeUnsigned(15);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(15);
                 output.writeUnsigned(symbolTable.lookup(statement.getClassName()));
             } catch (IOException e) {
                 throw new IOExceptionWrapper(e);
@@ -402,8 +436,8 @@ public class AstIO {
         @Override
         public void visit(MonitorEnterStatement statement) {
             try {
-                output.writeUnsigned(18);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(18);
                 writeExpr(statement.getObjectRef());
             } catch (IOException e) {
                 throw new IOExceptionWrapper(e);
@@ -413,8 +447,8 @@ public class AstIO {
         @Override
         public void visit(MonitorExitStatement statement) {
             try {
-                output.writeUnsigned(19);
                 writeLocation(statement.getLocation());
+                output.writeUnsigned(19);
                 writeExpr(statement.getObjectRef());
             } catch (IOException e) {
                 throw new IOExceptionWrapper(e);
@@ -636,18 +670,41 @@ public class AstIO {
     private TextLocation readLocation(VarDataInput input) throws IOException {
         int fileIndex = input.readUnsigned();
         if (fileIndex == 0) {
-            return null;
+            lastReadLocation = null;
+        } else if (fileIndex == 1) {
+            lastReadLocation = new TextLocation(lastReadLocation.getFileName(),
+                    lastReadLocation.getLine() + input.readSigned());
         } else {
-            return new TextLocation(fileTable.at(fileIndex - 1), input.readUnsigned());
+            lastReadLocation = new TextLocation(fileTable.at(fileIndex - 2), input.readUnsigned());
+            return lastReadLocation;
         }
+        return lastReadLocation;
+    }
+
+    private int readNodeLocation(int type, VarDataInput input) throws IOException {
+        switch (type) {
+            case 127:
+                lastReadLocation = null;
+                break;
+            case 126:
+                lastReadLocation = new TextLocation(lastReadLocation.getFileName(),
+                        lastReadLocation.getLine() + input.readSigned());
+                break;
+            case 125:
+                lastReadLocation = new TextLocation(fileTable.at(input.readUnsigned()), input.readUnsigned());
+                break;
+            default:
+                return type;
+        }
+        return input.readUnsigned();
     }
 
     private Statement readStatement(VarDataInput input) throws IOException {
-        int type = input.readUnsigned();
+        int type = readNodeLocation(input.readUnsigned(), input);
         switch (type) {
             case 0: {
                 AssignmentStatement stmt = new AssignmentStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setLeftValue(readExpr(input));
                 stmt.setRightValue(readExpr(input));
                 stmt.setAsync(input.readUnsigned() != 0);
@@ -655,7 +712,7 @@ public class AstIO {
             }
             case 1: {
                 AssignmentStatement stmt = new AssignmentStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setRightValue(readExpr(input));
                 stmt.setAsync(input.readUnsigned() != 0);
                 return stmt;
@@ -721,46 +778,46 @@ public class AstIO {
             }
             case 8: {
                 BreakStatement stmt = new BreakStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setTarget(statementMap.get(input.read()));
                 return stmt;
             }
             case 9: {
                 BreakStatement stmt = new BreakStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 return stmt;
             }
             case 10: {
                 ContinueStatement stmt = new ContinueStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setTarget(statementMap.get(input.read()));
                 return stmt;
             }
             case 11: {
                 ContinueStatement stmt = new ContinueStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 return stmt;
             }
             case 12: {
                 ReturnStatement stmt = new ReturnStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setResult(readExpr(input));
                 return stmt;
             }
             case 13: {
                 ReturnStatement stmt = new ReturnStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 return stmt;
             }
             case 14: {
                 ThrowStatement stmt = new ThrowStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setException(readExpr(input));
                 return stmt;
             }
             case 15: {
                 InitClassStatement stmt = new InitClassStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setClassName(symbolTable.at(input.readUnsigned()));
                 return stmt;
             }
@@ -785,13 +842,13 @@ public class AstIO {
             }
             case 18: {
                 MonitorEnterStatement stmt = new MonitorEnterStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setObjectRef(readExpr(input));
                 return stmt;
             }
             case 19: {
                 MonitorExitStatement stmt = new MonitorExitStatement();
-                stmt.setLocation(readLocation(input));
+                stmt.setLocation(lastReadLocation);
                 stmt.setObjectRef(readExpr(input));
                 return stmt;
             }
@@ -808,17 +865,11 @@ public class AstIO {
     }
 
     private Expr readExpr(VarDataInput input) throws IOException {
-        TextLocation location = readLocation(input);
-        Expr expr = readExprWithoutLocation(input);
-        expr.setLocation(location);
-        return expr;
-    }
-
-    private Expr readExprWithoutLocation(VarDataInput input) throws IOException {
-        int type = input.readUnsigned();
+        int type = readNodeLocation(input.readUnsigned(), input);
         switch (type) {
             case 0: {
                 BinaryExpr expr = new BinaryExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setOperation(binaryOperations[input.readUnsigned()]);
                 int valueType = input.readUnsigned();
                 expr.setType(valueType > 0 ? OperationType.values()[valueType - 1] : null);
@@ -828,6 +879,7 @@ public class AstIO {
             }
             case 1: {
                 UnaryExpr expr = new UnaryExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setOperation(unaryOperations[input.readUnsigned()]);
                 int valueType = input.readUnsigned();
                 expr.setType(valueType > 0 ? OperationType.values()[valueType - 1] : null);
@@ -836,16 +888,20 @@ public class AstIO {
             }
             case 2: {
                 ConditionalExpr expr = new ConditionalExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setCondition(readExpr(input));
                 expr.setConsequent(readExpr(input));
                 expr.setAlternative(readExpr(input));
                 return expr;
             }
             case 3: {
-                return new ConstantExpr();
+                ConstantExpr expr = new ConstantExpr();
+                expr.setLocation(lastReadLocation);
+                return expr;
             }
             case 4: {
                 ConstantExpr expr = new ConstantExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setValue(input.readSigned());
                 return expr;
             }
@@ -856,31 +912,37 @@ public class AstIO {
             }
             case 6: {
                 ConstantExpr expr = new ConstantExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setValue(input.readFloat());
                 return expr;
             }
             case 7: {
                 ConstantExpr expr = new ConstantExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setValue(input.readDouble());
                 return expr;
             }
             case 8: {
                 ConstantExpr expr = new ConstantExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setValue(input.read());
                 return expr;
             }
             case 9: {
                 ConstantExpr expr = new ConstantExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setValue(ValueType.parse(symbolTable.at(input.readUnsigned())));
                 return expr;
             }
             case 10: {
                 VariableExpr expr = new VariableExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setIndex(input.readUnsigned());
                 return expr;
             }
             case 11: {
                 SubscriptExpr expr = new SubscriptExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setArray(readExpr(input));
                 expr.setIndex(readExpr(input));
                 expr.setType(ArrayType.values()[input.readUnsigned()]);
@@ -888,6 +950,7 @@ public class AstIO {
             }
             case 12: {
                 UnwrapArrayExpr expr = new UnwrapArrayExpr(ArrayType.values()[input.readUnsigned()]);
+                expr.setLocation(lastReadLocation);
                 expr.setArray(readExpr(input));
                 return expr;
             }
@@ -901,6 +964,7 @@ public class AstIO {
                 return parseInvocationExpr(InvocationType.DYNAMIC, input);
             case 17: {
                 QualificationExpr expr = new QualificationExpr();
+                expr.setLocation(lastReadLocation);
                 String className = symbolTable.at(input.readUnsigned());
                 String fieldName = symbolTable.at(input.readUnsigned());
                 expr.setField(new FieldReference(className, fieldName));
@@ -908,6 +972,7 @@ public class AstIO {
             }
             case 18: {
                 QualificationExpr expr = new QualificationExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setQualified(readExpr(input));
                 String className = symbolTable.at(input.readUnsigned());
                 String fieldName = symbolTable.at(input.readUnsigned());
@@ -916,17 +981,20 @@ public class AstIO {
             }
             case 19: {
                 NewExpr expr = new NewExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setConstructedClass(symbolTable.at(input.readUnsigned()));
                 return expr;
             }
             case 20: {
                 NewArrayExpr expr = new NewArrayExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setLength(readExpr(input));
                 expr.setType(ValueType.parse(symbolTable.at(input.readUnsigned())));
                 return expr;
             }
             case 21: {
                 NewMultiArrayExpr expr = new NewMultiArrayExpr();
+                expr.setLocation(lastReadLocation);
                 int dimensionCount = input.readUnsigned();
                 for (int i = 0; i < dimensionCount; ++i) {
                     expr.getDimensions().add(readExpr(input));
@@ -936,18 +1004,21 @@ public class AstIO {
             }
             case 22: {
                 InstanceOfExpr expr = new InstanceOfExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setExpr(readExpr(input));
                 expr.setType(ValueType.parse(symbolTable.at(input.readUnsigned())));
                 return expr;
             }
             case 23: {
                 CastExpr expr = new CastExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setTarget(ValueType.parse(symbolTable.at(input.readUnsigned())));
                 expr.setValue(readExpr(input));
                 return expr;
             }
             case 24: {
                 PrimitiveCastExpr expr = new PrimitiveCastExpr();
+                expr.setLocation(lastReadLocation);
                 expr.setSource(OperationType.values()[input.readUnsigned()]);
                 expr.setTarget(OperationType.values()[input.readUnsigned()]);
                 expr.setValue(readExpr(input));
@@ -960,6 +1031,7 @@ public class AstIO {
 
     private InvocationExpr parseInvocationExpr(InvocationType invocationType, VarDataInput input) throws IOException {
         InvocationExpr expr = new InvocationExpr();
+        expr.setLocation(lastReadLocation);
         expr.setType(invocationType);
         String className = symbolTable.at(input.readUnsigned());
         String signature = symbolTable.at(input.readUnsigned());
diff --git a/core/src/main/java/org/teavm/cache/DiskCachedClassHolderSource.java b/core/src/main/java/org/teavm/cache/DiskCachedClassHolderSource.java
index dd268fafd..ce9a6d303 100644
--- a/core/src/main/java/org/teavm/cache/DiskCachedClassHolderSource.java
+++ b/core/src/main/java/org/teavm/cache/DiskCachedClassHolderSource.java
@@ -64,12 +64,13 @@ public class DiskCachedClassHolderSource implements ClassHolderSource, CacheStat
     private ProgramIO programIO;
 
     public DiskCachedClassHolderSource(File directory, ReferenceCache referenceCache, SymbolTable symbolTable,
-            SymbolTable fileTable, ClassHolderSource innerSource, ClassDateProvider classDateProvider) {
+            SymbolTable fileTable, SymbolTable variableTable, ClassHolderSource innerSource,
+            ClassDateProvider classDateProvider) {
         this.directory = directory;
         this.symbolTable = symbolTable;
         this.innerSource = innerSource;
         this.classDateProvider = classDateProvider;
-        programIO = new ProgramIO(referenceCache, symbolTable, fileTable);
+        programIO = new ProgramIO(referenceCache, symbolTable, fileTable, variableTable);
     }
 
     @Override
diff --git a/core/src/main/java/org/teavm/cache/DiskMethodNodeCache.java b/core/src/main/java/org/teavm/cache/DiskMethodNodeCache.java
index 56af8c319..726d4fd85 100644
--- a/core/src/main/java/org/teavm/cache/DiskMethodNodeCache.java
+++ b/core/src/main/java/org/teavm/cache/DiskMethodNodeCache.java
@@ -42,9 +42,9 @@ public class DiskMethodNodeCache implements MethodNodeCache {
     private final Set<MethodReference> newAsyncMethods = new HashSet<>();
 
     public DiskMethodNodeCache(File directory, ReferenceCache referenceCache, SymbolTable symbolTable,
-            SymbolTable fileTable) {
+            SymbolTable fileTable, SymbolTable variableTable) {
         this.directory = directory;
-        astIO = new AstIO(referenceCache, symbolTable, fileTable);
+        astIO = new AstIO(referenceCache, symbolTable, fileTable, variableTable);
     }
 
     @Override
diff --git a/core/src/main/java/org/teavm/cache/DiskProgramCache.java b/core/src/main/java/org/teavm/cache/DiskProgramCache.java
index 6123b3af7..0a7e572ad 100644
--- a/core/src/main/java/org/teavm/cache/DiskProgramCache.java
+++ b/core/src/main/java/org/teavm/cache/DiskProgramCache.java
@@ -27,13 +27,11 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.Supplier;
-import org.teavm.model.ClassReaderSource;
 import org.teavm.model.MethodReference;
 import org.teavm.model.Program;
 import org.teavm.model.ProgramCache;
@@ -46,9 +44,9 @@ public class DiskProgramCache implements ProgramCache {
     private Set<MethodReference> newMethods = new HashSet<>();
 
     public DiskProgramCache(File directory, ReferenceCache referenceCache, SymbolTable symbolTable,
-            SymbolTable fileTable) {
+            SymbolTable fileTable, SymbolTable variableTable) {
         this.directory = directory;
-        programIO = new ProgramIO(referenceCache, symbolTable, fileTable);
+        programIO = new ProgramIO(referenceCache, symbolTable, fileTable, variableTable);
     }
 
     @Override
@@ -90,8 +88,7 @@ public class DiskProgramCache implements ProgramCache {
         newMethods.add(method);
     }
 
-    public void flush(ClassReaderSource classSource) throws IOException {
-        Date currentTime = new Date();
+    public void flush() throws IOException {
         for (MethodReference method : newMethods) {
             Item item = cache.get(method);
             File file = getMethodFile(method);
diff --git a/core/src/main/java/org/teavm/cache/InMemoryMethodNodeCache.java b/core/src/main/java/org/teavm/cache/InMemoryMethodNodeCache.java
index 55983acd3..ca8d25702 100644
--- a/core/src/main/java/org/teavm/cache/InMemoryMethodNodeCache.java
+++ b/core/src/main/java/org/teavm/cache/InMemoryMethodNodeCache.java
@@ -36,8 +36,8 @@ public class InMemoryMethodNodeCache implements MethodNodeCache {
     private AstIO io;
 
     public InMemoryMethodNodeCache(ReferenceCache referenceCache, InMemorySymbolTable symbolTable,
-            InMemorySymbolTable fileSymbolTable) {
-        io = new AstIO(referenceCache, symbolTable, fileSymbolTable);
+            InMemorySymbolTable fileSymbolTable, InMemorySymbolTable variableSymbolTable) {
+        io = new AstIO(referenceCache, symbolTable, fileSymbolTable, variableSymbolTable);
     }
 
     @Override
diff --git a/core/src/main/java/org/teavm/cache/InMemoryProgramCache.java b/core/src/main/java/org/teavm/cache/InMemoryProgramCache.java
index 9107327ee..d90e08473 100644
--- a/core/src/main/java/org/teavm/cache/InMemoryProgramCache.java
+++ b/core/src/main/java/org/teavm/cache/InMemoryProgramCache.java
@@ -33,8 +33,8 @@ public class InMemoryProgramCache implements ProgramCache {
     private ProgramIO io;
 
     public InMemoryProgramCache(ReferenceCache referenceCache, InMemorySymbolTable symbolTable,
-            InMemorySymbolTable fileSymbolTable) {
-        io = new ProgramIO(referenceCache, symbolTable, fileSymbolTable);
+            InMemorySymbolTable fileSymbolTable, InMemorySymbolTable variableSymbolTable) {
+        io = new ProgramIO(referenceCache, symbolTable, fileSymbolTable, variableSymbolTable);
     }
 
     @Override
diff --git a/core/src/main/java/org/teavm/cache/ProgramIO.java b/core/src/main/java/org/teavm/cache/ProgramIO.java
index f656c129e..ce062286c 100644
--- a/core/src/main/java/org/teavm/cache/ProgramIO.java
+++ b/core/src/main/java/org/teavm/cache/ProgramIO.java
@@ -85,6 +85,7 @@ import org.teavm.model.instructions.UnwrapArrayInstruction;
 public class ProgramIO {
     private SymbolTable symbolTable;
     private SymbolTable fileTable;
+    private SymbolTable variableTable;
     private ReferenceCache referenceCache;
     private static BinaryOperation[] binaryOperations = BinaryOperation.values();
     private static NumericOperandType[] numericOperandTypes = NumericOperandType.values();
@@ -94,10 +95,12 @@ public class ProgramIO {
     private static BinaryBranchingCondition[] binaryBranchingConditions = BinaryBranchingCondition.values();
     private static ArrayElementType[] arrayElementTypes = ArrayElementType.values();
 
-    public ProgramIO(ReferenceCache referenceCache, SymbolTable symbolTable, SymbolTable fileTable) {
+    public ProgramIO(ReferenceCache referenceCache, SymbolTable symbolTable, SymbolTable fileTable,
+            SymbolTable variableTable) {
         this.referenceCache = referenceCache;
         this.symbolTable = symbolTable;
         this.fileTable = fileTable;
+        this.variableTable = variableTable;
     }
 
     public void write(Program program, OutputStream output) throws IOException {
@@ -107,7 +110,7 @@ public class ProgramIO {
         for (int i = 0; i < program.variableCount(); ++i) {
             Variable var = program.variableAt(i);
             data.writeUnsigned(var.getRegister());
-            data.write(var.getDebugName());
+            data.writeUnsigned(var.getDebugName() != null ? variableTable.lookup(var.getDebugName()) + 1 : 0);
         }
         for (int i = 0; i < program.basicBlockCount(); ++i) {
             BasicBlock basicBlock = program.basicBlockAt(i);
@@ -133,13 +136,20 @@ public class ProgramIO {
             for (Instruction insn : basicBlock) {
                 try {
                     if (!Objects.equals(location, insn.getLocation())) {
-                        location = insn.getLocation();
-                        if (location == null || location.getFileName() == null || location.getLine() < 0) {
+                        TextLocation newLocation = insn.getLocation();
+                        if (newLocation == null || newLocation.getFileName() == null || newLocation.getLine() < 0) {
                             data.writeUnsigned(1);
+                            location = null;
                         } else {
-                            data.writeUnsigned(2);
-                            data.writeUnsigned(fileTable.lookup(location.getFileName()));
-                            data.writeUnsigned(location.getLine());
+                            if (location != null && location.getFileName().equals(newLocation.getFileName())) {
+                                data.writeUnsigned(127);
+                                data.writeSigned(newLocation.getLine() - location.getLine());
+                            } else {
+                                data.writeUnsigned(2);
+                                data.writeUnsigned(fileTable.lookup(newLocation.getFileName()));
+                                data.writeUnsigned(newLocation.getLine());
+                            }
+                            location = newLocation;
                         }
                     }
                     insn.acceptVisitor(insnWriter);
@@ -159,7 +169,8 @@ public class ProgramIO {
         for (int i = 0; i < varCount; ++i) {
             Variable var = program.createVariable();
             var.setRegister(data.readUnsigned());
-            var.setDebugName(referenceCache.getCached(data.read()));
+            int nameIndex = data.readUnsigned();
+            var.setDebugName(nameIndex != 0 ? referenceCache.getCached(variableTable.at(nameIndex - 1)) : null);
         }
         for (int i = 0; i < basicBlockCount; ++i) {
             program.createBasicBlock();
@@ -212,6 +223,11 @@ public class ProgramIO {
                         location = new TextLocation(file, line);
                         break;
                     }
+                    case 127: {
+                        int line = location.getLine() + data.readSigned();
+                        location = new TextLocation(location.getFileName(), line);
+                        break;
+                    }
                     default: {
                         Instruction insn = readInstruction(insnType, program, data);
                         insn.setLocation(location);
diff --git a/core/src/main/java/org/teavm/cache/VarDataInput.java b/core/src/main/java/org/teavm/cache/VarDataInput.java
index beb73d771..0cd611066 100644
--- a/core/src/main/java/org/teavm/cache/VarDataInput.java
+++ b/core/src/main/java/org/teavm/cache/VarDataInput.java
@@ -69,7 +69,15 @@ public class VarDataInput {
     }
 
     public float readFloat() throws IOException {
-        int exponent = readSigned() + 127;
+        int exponent = readUnsigned();
+        if (exponent == 0) {
+            return 0;
+        }
+
+        exponent--;
+        exponent = (exponent & 1) == 0 ? exponent >>> 1 : -(exponent >>> 1);
+        exponent += 127;
+
         int mantissa = Integer.reverse(readUnsigned()) >>> 8;
         boolean sign = (mantissa & (1 << 23)) != 0;
 
@@ -83,7 +91,15 @@ public class VarDataInput {
     }
 
     public double readDouble() throws IOException {
-        int exponent = readSigned() + 1023;
+        int exponent = readUnsigned();
+        if (exponent == 0) {
+            return 0;
+        }
+
+        exponent--;
+        exponent = (exponent & 1) == 0 ? exponent >>> 1 : -(exponent >>> 1);
+        exponent += 1023;
+
         long mantissa = Long.reverse(readUnsignedLong()) >>> 11;
         boolean sign = (mantissa & (1L << 52)) != 0;
 
diff --git a/core/src/main/java/org/teavm/cache/VarDataOutput.java b/core/src/main/java/org/teavm/cache/VarDataOutput.java
index 9a7bd571a..e64405457 100644
--- a/core/src/main/java/org/teavm/cache/VarDataOutput.java
+++ b/core/src/main/java/org/teavm/cache/VarDataOutput.java
@@ -53,6 +53,10 @@ public class VarDataOutput implements Closeable {
     }
 
     public void writeFloat(float value) throws IOException {
+        if (value == 0) {
+            writeUnsigned(0);
+            return;
+        }
         int bits = Float.floatToRawIntBits(value);
         boolean sign = (bits & (1 << 31)) != 0;
         int exponent = (bits >> 23) & ((1 << 8) - 1);
@@ -60,11 +64,16 @@ public class VarDataOutput implements Closeable {
         if (sign) {
             mantissa |= 1 << 23;
         }
-        writeSigned(exponent - 127);
+        exponent -= 127;
+        writeUnsigned(1 + (exponent > 0 ? exponent << 1 : 1 | (-exponent << 1)));
         writeUnsigned(Integer.reverse(mantissa << 8));
     }
 
     public void writeDouble(double value) throws IOException {
+        if (value == 0) {
+            writeUnsigned(0);
+            return;
+        }
         long bits = Double.doubleToRawLongBits(value);
         boolean sign = (bits & (1L << 63)) != 0;
         int exponent = (int) (bits >> 52) & ((1 << 11) - 1);
@@ -72,7 +81,8 @@ public class VarDataOutput implements Closeable {
         if (sign) {
             mantissa |= 1L << 52;
         }
-        writeSigned(exponent - 1023);
+        exponent -= 1023;
+        writeUnsigned(1 + (exponent > 0 ? exponent << 1 : 1 | (-exponent << 1)));
         writeUnsigned(Long.reverse(mantissa << 11));
     }
 
diff --git a/core/src/main/java/org/teavm/debugging/information/DebugInformation.java b/core/src/main/java/org/teavm/debugging/information/DebugInformation.java
index 557dbb7ca..6e6592169 100644
--- a/core/src/main/java/org/teavm/debugging/information/DebugInformation.java
+++ b/core/src/main/java/org/teavm/debugging/information/DebugInformation.java
@@ -53,6 +53,10 @@ public class DebugInformation {
     MethodTree methodTree;
     ReferenceCache referenceCache;
 
+    public DebugInformation() {
+        this(new ReferenceCache());
+    }
+
     public DebugInformation(ReferenceCache referenceCache) {
         this.referenceCache = referenceCache;
     }
diff --git a/core/src/main/java/org/teavm/dependency/DependencyAnalyzer.java b/core/src/main/java/org/teavm/dependency/DependencyAnalyzer.java
index 64e3d601f..dfa133ed8 100644
--- a/core/src/main/java/org/teavm/dependency/DependencyAnalyzer.java
+++ b/core/src/main/java/org/teavm/dependency/DependencyAnalyzer.java
@@ -26,7 +26,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.Deque;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
@@ -37,7 +36,6 @@ import org.objectweb.asm.tree.ClassNode;
 import org.teavm.cache.IncrementalDependencyProvider;
 import org.teavm.cache.IncrementalDependencyRegistration;
 import org.teavm.callgraph.CallGraph;
-import org.teavm.callgraph.CallGraphNode;
 import org.teavm.callgraph.DefaultCallGraph;
 import org.teavm.common.CachedMapper;
 import org.teavm.common.Mapper;
@@ -429,8 +427,7 @@ public abstract class DependencyAnalyzer implements DependencyInfo {
 
     private ClassDependency createClassDependency(String className) {
         ClassReader cls = classSource.get(className);
-        ClassDependency dependency = new ClassDependency(this, className, cls);
-        return dependency;
+        return new ClassDependency(this, className, cls);
     }
 
     public MethodDependency linkMethod(String className, MethodDescriptor descriptor) {
@@ -527,8 +524,6 @@ public abstract class DependencyAnalyzer implements DependencyInfo {
         return classCache.getCachedPreimages();
     }
 
-    private Set<FieldReference> fieldsAddedByRoot = new HashSet<>();
-
     public FieldDependency linkField(FieldReference fieldRef) {
         FieldDependency dep = fieldCache.map(fieldRef);
         if (!dep.activated) {
@@ -746,9 +741,25 @@ public abstract class DependencyAnalyzer implements DependencyInfo {
             }
         }
 
+        for (Map<?, MethodDependency> map : methodCache.values()) {
+            for (MethodDependency methodDependency : map.values()) {
+                methodDependency.locationListeners = null;
+                methodDependency.locations = null;
+            }
+        }
+
+        for (FieldReference fieldRef : fieldCache.getCachedPreimages()) {
+            FieldDependency field = fieldCache.getKnown(fieldRef);
+            if (field != null) {
+                field.locationListeners = null;
+                field.locations = null;
+            }
+        }
+
         allNodes.clear();
         classSource.cleanup();
         agent.cleanup();
+        listeners.clear();
     }
 
     public void cleanupTypes() {
@@ -857,10 +868,7 @@ public abstract class DependencyAnalyzer implements DependencyInfo {
             return;
         }
 
-        CallGraphNode caller = callGraph.getNode(methodDep.getReference());
-
         ProgramEmitter pe = ProgramEmitter.create(program, classHierarchy);
-        boolean hasIndy = false;
         BasicBlockSplitter splitter = new BasicBlockSplitter(program);
         for (int i = 0; i < program.basicBlockCount(); ++i) {
             BasicBlock block = program.basicBlockAt(i);
@@ -885,7 +893,6 @@ public abstract class DependencyAnalyzer implements DependencyInfo {
                     continue;
                 }
 
-                hasIndy = true;
                 BasicBlock splitBlock = splitter.split(block, insn);
 
                 pe.enter(block);
@@ -910,7 +917,6 @@ public abstract class DependencyAnalyzer implements DependencyInfo {
                     pe.addInstruction(assign);
                 }
                 pe.jump(splitBlock);
-                block = splitBlock;
             }
         }
         splitter.fixProgram();
diff --git a/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java b/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java
index a914bb1a9..cadd1c614 100644
--- a/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java
+++ b/core/src/main/java/org/teavm/dependency/FastDependencyAnalyzer.java
@@ -189,4 +189,11 @@ public class FastDependencyAnalyzer extends DependencyAnalyzer {
     boolean domainOptimizationEnabled() {
         return false;
     }
+
+    @Override
+    public void cleanup() {
+        virtualCallConsumers.clear();
+        subtypeNodes.clear();
+        super.cleanup();
+    }
 }
diff --git a/core/src/main/java/org/teavm/dependency/FieldDependency.java b/core/src/main/java/org/teavm/dependency/FieldDependency.java
index 253a31415..5df70a43a 100644
--- a/core/src/main/java/org/teavm/dependency/FieldDependency.java
+++ b/core/src/main/java/org/teavm/dependency/FieldDependency.java
@@ -28,8 +28,8 @@ public class FieldDependency implements FieldDependencyInfo {
     DependencyNode value;
     private FieldReader field;
     private FieldReference reference;
-    private List<LocationListener> locationListeners;
-    private Set<CallLocation> locations;
+    List<LocationListener> locationListeners;
+    Set<CallLocation> locations;
     boolean activated;
 
     FieldDependency(DependencyNode value, FieldReader field, FieldReference reference) {
diff --git a/core/src/main/java/org/teavm/dependency/MethodDependency.java b/core/src/main/java/org/teavm/dependency/MethodDependency.java
index b68523316..db0a60806 100644
--- a/core/src/main/java/org/teavm/dependency/MethodDependency.java
+++ b/core/src/main/java/org/teavm/dependency/MethodDependency.java
@@ -38,8 +38,8 @@ public class MethodDependency implements MethodDependencyInfo {
     boolean external;
     DependencyPlugin dependencyPlugin;
     boolean dependencyPluginAttached;
-    private List<LocationListener> locationListeners;
-    private Set<CallLocation> locations;
+    List<LocationListener> locationListeners;
+    Set<CallLocation> locations;
     boolean activated;
 
     MethodDependency(DependencyAnalyzer dependencyAnalyzer, DependencyNode[] variableNodes, int parameterCount,
diff --git a/core/src/main/java/org/teavm/model/MethodDescriptor.java b/core/src/main/java/org/teavm/model/MethodDescriptor.java
index 6fdbf3ee7..35d0ae460 100644
--- a/core/src/main/java/org/teavm/model/MethodDescriptor.java
+++ b/core/src/main/java/org/teavm/model/MethodDescriptor.java
@@ -20,7 +20,7 @@ import java.util.Arrays;
 public class MethodDescriptor {
     private String name;
     private ValueType[] signature;
-    private volatile String reprCache;
+    private int hash;
 
     public MethodDescriptor(String name, ValueType... signature) {
         if (signature.length < 1) {
@@ -70,10 +70,7 @@ public class MethodDescriptor {
 
     @Override
     public String toString() {
-        if (reprCache == null) {
-            reprCache = name + signatureToString();
-        }
-        return reprCache;
+        return name + signatureToString();
     }
 
     public String signatureToString() {
@@ -140,17 +137,43 @@ public class MethodDescriptor {
 
     @Override
     public int hashCode() {
-        return toString().hashCode();
+        if (hash == 0) {
+            hash = name.hashCode();
+            for (ValueType param : signature) {
+                hash = 31 * hash + param.hashCode();
+            }
+            if (hash == 0) {
+                hash++;
+            }
+        }
+
+        return hash;
     }
 
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
-         }
-         if (!(obj instanceof MethodDescriptor)) {
-             return false;
-         }
-         return toString().equals(obj.toString());
+        }
+        if (!(obj instanceof MethodDescriptor)) {
+            return false;
+        }
+        MethodDescriptor that = (MethodDescriptor) obj;
+
+        if (signature.length != that.signature.length) {
+            return false;
+        }
+
+        if (!name.equals(that.name)) {
+            return false;
+        }
+
+        for (int i = 0; i < signature.length; ++i) {
+            if (!signature[i].equals(that.signature[i])) {
+                return false;
+            }
+        }
+
+        return true;
     }
 }
diff --git a/core/src/main/java/org/teavm/model/MethodReference.java b/core/src/main/java/org/teavm/model/MethodReference.java
index 4d4dd13c5..6f0ed370c 100644
--- a/core/src/main/java/org/teavm/model/MethodReference.java
+++ b/core/src/main/java/org/teavm/model/MethodReference.java
@@ -35,16 +35,12 @@ import java.util.stream.Stream;
  */
 public class MethodReference implements Serializable {
     private String className;
-    private String name;
-    private ValueType[] signature;
     private transient MethodDescriptor descriptor;
-    private transient String reprCache;
+    private int hash;
 
     public MethodReference(String className, MethodDescriptor descriptor) {
         this.className = className;
         this.descriptor = descriptor;
-        this.name = descriptor.getName();
-        this.signature = descriptor.getSignature();
     }
 
     /**
@@ -64,9 +60,7 @@ public class MethodReference implements Serializable {
      * a type of a returning value, and all the remaining elements are types of arguments.
      */
     public MethodReference(String className, String name, ValueType... signature) {
-        this.className = className;
-        this.name = name;
-        this.signature = Arrays.copyOf(signature, signature.length);
+        this(className, new MethodDescriptor(name, signature));
     }
 
     public MethodReference(Class<?> cls, String name, Class<?>... signature) {
@@ -86,42 +80,42 @@ public class MethodReference implements Serializable {
     }
 
     public MethodDescriptor getDescriptor() {
-        if (descriptor == null) {
-            descriptor = new MethodDescriptor(name, signature);
-        }
         return descriptor;
     }
 
     public int parameterCount() {
-        return signature.length - 1;
+        return descriptor.parameterCount();
     }
 
     public ValueType parameterType(int index) {
-        if (index >= signature.length + 1) {
-            throw new IndexOutOfBoundsException("Index " + index + " is greater than size " + (signature.length - 1));
-        }
-        return signature[index];
+        return descriptor.parameterType(index);
     }
 
     public ValueType[] getParameterTypes() {
-        return Arrays.copyOf(signature, signature.length - 1);
+        return descriptor.getParameterTypes();
     }
 
     public ValueType[] getSignature() {
-        return Arrays.copyOf(signature, signature.length);
+        return descriptor.getSignature();
     }
 
     public ValueType getReturnType() {
-        return signature[signature.length - 1];
+        return descriptor.getResultType();
     }
 
     public String getName() {
-        return name;
+        return descriptor.getName();
     }
 
     @Override
     public int hashCode() {
-        return toString().hashCode();
+        if (hash == 0) {
+            hash = (className.hashCode() * 31 + descriptor.hashCode()) * 17;
+            if (hash == 0) {
+                hash++;
+            }
+        }
+        return hash;
     }
 
     @Override
@@ -132,17 +126,15 @@ public class MethodReference implements Serializable {
         if (!(obj instanceof MethodReference)) {
             return false;
         }
+
         MethodReference other = (MethodReference) obj;
-        return toString().equals(other.toString());
+        return className.equals(other.className) && descriptor.equals(other.descriptor);
     }
 
     @Override
     @JsonValue
     public String toString() {
-        if (reprCache == null) {
-            reprCache = className + "." + getDescriptor().toString();
-        }
-        return reprCache;
+        return className + "." + getDescriptor().toString();
     }
 
     @JsonCreator
diff --git a/core/src/main/java/org/teavm/model/ValueType.java b/core/src/main/java/org/teavm/model/ValueType.java
index d554f643d..767b24372 100644
--- a/core/src/main/java/org/teavm/model/ValueType.java
+++ b/core/src/main/java/org/teavm/model/ValueType.java
@@ -20,7 +20,6 @@ import java.util.*;
 import java.util.stream.Collectors;
 
 public abstract class ValueType implements Serializable {
-    volatile String reprCache;
     private static final Map<Class<?>, ValueType> primitiveMap = new HashMap<>();
 
     private ValueType() {
@@ -28,6 +27,7 @@ public abstract class ValueType implements Serializable {
 
     public static class Object extends ValueType {
         private String className;
+        private int hash;
 
         public Object(String className) {
             this.className = className;
@@ -39,23 +39,45 @@ public abstract class ValueType implements Serializable {
 
         @Override
         public String toString() {
-            if (reprCache == null) {
-                reprCache = "L" + className.replace('.', '/') + ";";
-            }
-            return reprCache;
+            return "L" + className.replace('.', '/') + ";";
         }
 
         @Override
         public boolean isObject(String className) {
             return this.className.equals(className);
         }
+
+        @Override
+        public boolean equals(java.lang.Object obj) {
+            if (obj == this) {
+                return true;
+            }
+            if (!(obj instanceof Object)) {
+                return false;
+            }
+            Object that = (Object) obj;
+            return that.className.equals(className);
+        }
+
+        @Override
+        public int hashCode() {
+            if (hash == 0) {
+                hash = 85396296 ^ (className.hashCode() * 167);
+                if (hash == 0) {
+                    ++hash;
+                }
+            }
+            return hash;
+        }
     }
 
     public static class Primitive extends ValueType {
         private PrimitiveType kind;
+        private int hash;
 
-        Primitive(PrimitiveType kind) {
+        private Primitive(PrimitiveType kind) {
             this.kind = kind;
+            hash = 17988782 ^ (kind.ordinal() * 31);
         }
 
         public PrimitiveType getKind() {
@@ -64,13 +86,6 @@ public abstract class ValueType implements Serializable {
 
         @Override
         public String toString() {
-            if (reprCache == null) {
-                reprCache = createString();
-            }
-            return reprCache;
-        }
-
-        private String createString() {
             switch (kind) {
                 case BOOLEAN:
                     return "Z";
@@ -97,10 +112,21 @@ public abstract class ValueType implements Serializable {
         public boolean isObject(String cls) {
             return false;
         }
+
+        @Override
+        public boolean equals(java.lang.Object obj) {
+            return this == obj;
+        }
+
+        @Override
+        public int hashCode() {
+            return hash;
+        }
     }
 
     public static class Array extends ValueType {
         private ValueType itemType;
+        private int hash;
 
         public Array(ValueType itemType) {
             this.itemType = itemType;
@@ -112,19 +138,43 @@ public abstract class ValueType implements Serializable {
 
         @Override
         public String toString() {
-            if (reprCache == null) {
-                reprCache = "[" + itemType.toString();
-            }
-            return reprCache;
+            return "[" + itemType;
         }
 
         @Override
         public boolean isObject(String cls) {
             return false;
         }
+
+        @Override
+        public boolean equals(java.lang.Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (!(obj instanceof Array)) {
+                return false;
+            }
+
+            Array that = (Array) obj;
+            return itemType.equals(that.itemType);
+        }
+
+        @Override
+        public int hashCode() {
+            if (hash == 0) {
+                hash = 27039876 ^ (itemType.hashCode() * 193);
+                if (hash == 0) {
+                    ++hash;
+                }
+            }
+            return hash;
+        }
     }
 
     public static class Void extends ValueType {
+        private Void() {
+        }
+
         @Override
         public String toString() {
             return "V";
@@ -134,12 +184,15 @@ public abstract class ValueType implements Serializable {
         public boolean isObject(String cls) {
             return false;
         }
-    }
 
-    public static class Null extends ValueType {
         @Override
-        public boolean isObject(String cls) {
-            return false;
+        public boolean equals(java.lang.Object obj) {
+            return this == obj;
+        }
+
+        @Override
+        public int hashCode() {
+            return 53604390;
         }
     }
 
@@ -161,9 +214,6 @@ public abstract class ValueType implements Serializable {
 
     public static final Primitive CHARACTER = new Primitive(PrimitiveType.CHARACTER);
 
-    public static final Null NULL = new Null();
-
-
     static {
         primitiveMap.put(boolean.class, BOOLEAN);
         primitiveMap.put(char.class, CHARACTER);
@@ -227,7 +277,7 @@ public abstract class ValueType implements Serializable {
             types.add(type);
             index = nextIndex;
         }
-        return types.toArray(new ValueType[types.size()]);
+        return types.toArray(new ValueType[0]);
     }
 
     private static int cut(String text, int index) {
@@ -344,20 +394,4 @@ public abstract class ValueType implements Serializable {
             return ValueType.object(cls.getName());
         }
     }
-
-    @Override
-    public int hashCode() {
-        return toString().hashCode();
-    }
-
-    @Override
-    public boolean equals(java.lang.Object obj) {
-        if (this == obj) {
-           return true;
-        }
-        if (!(obj instanceof ValueType)) {
-            return false;
-        }
-        return toString().equals(obj.toString());
-    }
 }
diff --git a/core/src/test/java/org/teavm/cache/ProgramIOTest.java b/core/src/test/java/org/teavm/cache/ProgramIOTest.java
index a0efe92bf..985810ff8 100644
--- a/core/src/test/java/org/teavm/cache/ProgramIOTest.java
+++ b/core/src/test/java/org/teavm/cache/ProgramIOTest.java
@@ -158,7 +158,8 @@ public class ProgramIOTest {
     private Program inputOutput(Program program) {
         InMemorySymbolTable symbolTable = new InMemorySymbolTable();
         InMemorySymbolTable fileTable = new InMemorySymbolTable();
-        ProgramIO programIO = new ProgramIO(new ReferenceCache(), symbolTable, fileTable);
+        InMemorySymbolTable variableTable = new InMemorySymbolTable();
+        ProgramIO programIO = new ProgramIO(new ReferenceCache(), symbolTable, fileTable, variableTable);
         try (ByteArrayOutputStream output = new ByteArrayOutputStream()) {
             programIO.write(program, output);
             try (ByteArrayInputStream input = new ByteArrayInputStream(output.toByteArray())) {
diff --git a/tests/src/test/java/org/teavm/incremental/IncrementalTest.java b/tests/src/test/java/org/teavm/incremental/IncrementalTest.java
index 782b5cba0..5704a0d4b 100644
--- a/tests/src/test/java/org/teavm/incremental/IncrementalTest.java
+++ b/tests/src/test/java/org/teavm/incremental/IncrementalTest.java
@@ -239,7 +239,8 @@ public class IncrementalTest {
         boolean capturing;
 
         CapturingMethodNodeCache() {
-            super(new ReferenceCache(), new InMemorySymbolTable(), new InMemorySymbolTable());
+            super(new ReferenceCache(), new InMemorySymbolTable(), new InMemorySymbolTable(),
+                    new InMemorySymbolTable());
         }
 
         @Override
@@ -264,7 +265,8 @@ public class IncrementalTest {
         boolean capturing;
 
         CapturingProgramCache() {
-            super(new ReferenceCache(), new InMemorySymbolTable(), new InMemorySymbolTable());
+            super(new ReferenceCache(), new InMemorySymbolTable(), new InMemorySymbolTable(),
+                    new InMemorySymbolTable());
         }
 
         @Override
diff --git a/tools/core/src/main/java/org/teavm/tooling/TeaVMTool.java b/tools/core/src/main/java/org/teavm/tooling/TeaVMTool.java
index aa4b10143..c809fff65 100644
--- a/tools/core/src/main/java/org/teavm/tooling/TeaVMTool.java
+++ b/tools/core/src/main/java/org/teavm/tooling/TeaVMTool.java
@@ -88,6 +88,7 @@ public class TeaVMTool {
     private DiskMethodNodeCache astCache;
     private FileSymbolTable symbolTable;
     private FileSymbolTable fileTable;
+    private FileSymbolTable variableTable;
     private boolean cancelled;
     private TeaVMProgressListener progressListener;
     private TeaVM vm;
@@ -327,27 +328,31 @@ public class TeaVMTool {
         try {
             cancelled = false;
             log.info("Running TeaVM");
+            referenceCache = new ReferenceCache();
             TeaVMBuilder vmBuilder = new TeaVMBuilder(prepareTarget());
             CacheStatus cacheStatus;
-            referenceCache = new ReferenceCache();
             vmBuilder.setReferenceCache(referenceCache);
             if (incremental) {
                 cacheDirectory.mkdirs();
                 symbolTable = new FileSymbolTable(new File(cacheDirectory, "symbols"));
                 fileTable = new FileSymbolTable(new File(cacheDirectory, "files"));
+                variableTable = new FileSymbolTable(new File(cacheDirectory, "variables"));
                 ClasspathClassHolderSource innerClassSource = new ClasspathClassHolderSource(classLoader,
                         referenceCache);
                 ClassHolderSource classSource = new PreOptimizingClassHolderSource(innerClassSource);
                 cachedClassSource = new DiskCachedClassHolderSource(cacheDirectory, referenceCache, symbolTable,
-                        fileTable, classSource, innerClassSource);
-                programCache = new DiskProgramCache(cacheDirectory, referenceCache, symbolTable, fileTable);
+                        fileTable, variableTable, classSource, innerClassSource);
+                programCache = new DiskProgramCache(cacheDirectory, referenceCache, symbolTable, fileTable,
+                        variableTable);
                 if (incremental && targetType == TeaVMTargetType.JAVASCRIPT) {
-                    astCache = new DiskMethodNodeCache(cacheDirectory, referenceCache, symbolTable, fileTable);
+                    astCache = new DiskMethodNodeCache(cacheDirectory, referenceCache, symbolTable, fileTable,
+                            variableTable);
                     javaScriptTarget.setAstCache(astCache);
                 }
                 try {
                     symbolTable.update();
                     fileTable.update();
+                    variableTable.update();
                 } catch (IOException e) {
                     log.info("Cache is missing");
                 }
@@ -420,13 +425,14 @@ public class TeaVMTool {
             }
 
             if (incremental) {
-                programCache.flush(vm.getDependencyClassSource());
+                programCache.flush();
                 if (astCache != null) {
                     astCache.flush();
                 }
                 cachedClassSource.flush();
                 symbolTable.flush();
                 fileTable.flush();
+                variableTable.flush();
                 log.info("Cache updated");
             }
 
diff --git a/tools/devserver/src/main/java/org/teavm/devserver/CodeServlet.java b/tools/devserver/src/main/java/org/teavm/devserver/CodeServlet.java
index 89a65d7b9..e8b56af6c 100644
--- a/tools/devserver/src/main/java/org/teavm/devserver/CodeServlet.java
+++ b/tools/devserver/src/main/java/org/teavm/devserver/CodeServlet.java
@@ -140,6 +140,7 @@ public class CodeServlet extends HttpServlet {
     private WebSocketClient wsClient = new WebSocketClient();
     private InMemorySymbolTable symbolTable = new InMemorySymbolTable();
     private InMemorySymbolTable fileSymbolTable = new InMemorySymbolTable();
+    private InMemorySymbolTable variableSymbolTable = new InMemorySymbolTable();
     private ReferenceCache referenceCache = new ReferenceCache();
 
     public CodeServlet(String mainClass, String[] classPath) {
@@ -709,8 +710,8 @@ public class CodeServlet extends HttpServlet {
         watcher = new FileSystemWatcher(classPath);
 
         classSource = new MemoryCachedClassReaderSource();
-        astCache = new InMemoryMethodNodeCache(referenceCache, symbolTable, fileSymbolTable);
-        programCache = new InMemoryProgramCache(referenceCache, symbolTable, fileSymbolTable);
+        astCache = new InMemoryMethodNodeCache(referenceCache, symbolTable, fileSymbolTable, variableSymbolTable);
+        programCache = new InMemoryProgramCache(referenceCache, symbolTable, fileSymbolTable, variableSymbolTable);
     }
 
     private void shutdownBuilder() {