diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java
index da31f6f15e8..cf7f135ea97 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java
@@ -16,8 +16,6 @@
 
 package org.jetbrains.jet.lang.resolve.lazy;
 
-import com.google.common.collect.Lists;
-import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -29,6 +27,7 @@ import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
 
 import java.util.*;
+import java.util.concurrent.ConcurrentMap;
 
 import static org.jetbrains.jet.lang.resolve.lazy.ResolveSessionUtils.safeNameForLazyResolve;
 
@@ -37,15 +36,14 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
     protected final DP declarationProvider;
     protected final D thisDescriptor;
 
-    protected boolean allDescriptorsComputed = false;
+    private final ConcurrentMap<Name, ClassDescriptor> classDescriptors;
+    private final ConcurrentMap<Name, ClassDescriptor> objectDescriptors;
 
-    private final Map<Name, ClassDescriptor> classDescriptors = Maps.newHashMap();
-    private final Map<Name, ClassDescriptor> objectDescriptors = Maps.newHashMap();
+    private final ConcurrentMap<Name, Set<FunctionDescriptor>> functionDescriptors;
+    private final ConcurrentMap<Name, Set<VariableDescriptor>> propertyDescriptors;
 
-    protected final Map<Name, Set<FunctionDescriptor>> functionDescriptors = Maps.newHashMap();
-    private final Map<Name, Set<VariableDescriptor>> propertyDescriptors = Maps.newHashMap();
-
-    protected final List<DeclarationDescriptor> allDescriptors = Lists.newArrayList();
+    private final Collection<DeclarationDescriptor> allDescriptors;
+    protected volatile boolean allDescriptorsComputed = false;
 
     protected AbstractLazyMemberScope(
             @NotNull ResolveSession resolveSession,
@@ -55,10 +53,17 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
         this.resolveSession = resolveSession;
         this.declarationProvider = declarationProvider;
         this.thisDescriptor = thisDescriptor;
+
+        StorageManager storageManager = resolveSession.getStorageManager();
+        this.classDescriptors = storageManager.createConcurrentMap();
+        this.objectDescriptors = storageManager.createConcurrentMap();
+        this.functionDescriptors = storageManager.createConcurrentMap();
+        this.propertyDescriptors = storageManager.createConcurrentMap();
+        this.allDescriptors = storageManager.createConcurrentCollection();
     }
 
     @Nullable
-    private ClassDescriptor getClassOrObjectDescriptor(@NotNull Map<Name, ClassDescriptor> cache, @NotNull Name name, boolean object) {
+    private ClassDescriptor getClassOrObjectDescriptor(@NotNull ConcurrentMap<Name, ClassDescriptor> cache, @NotNull Name name, boolean object) {
         ClassDescriptor known = cache.get(name);
         if (known != null) return known;
 
@@ -77,9 +82,11 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
             ClassDescriptor classDescriptor = new LazyClassDescriptor(resolveSession, thisDescriptor, name,
                                                                       JetClassInfoUtil.createClassLikeInfo(classOrObjectDeclaration));
 
-            cache.put(name, classDescriptor);
+            ClassDescriptor oldValue = cache.putIfAbsent(name, classDescriptor);
+            if (oldValue != null) return oldValue;
+
             if (!object) {
-                allDescriptors.add(classDescriptor);
+                registerDescriptor(classDescriptor);
             }
 
             result = classDescriptor;
@@ -123,8 +130,10 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
         getNonDeclaredFunctions(name, result);
 
         if (!result.isEmpty()) {
-            functionDescriptors.put(name, result);
-            allDescriptors.addAll(result);
+            Set<FunctionDescriptor> oldValue = functionDescriptors.putIfAbsent(name, result);
+            if (oldValue != null) return oldValue;
+
+            registerDescriptors(result);
         }
         return result;
     }
@@ -170,8 +179,10 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
         getNonDeclaredProperties(name, result);
 
         if (!result.isEmpty()) {
-            propertyDescriptors.put(name, result);
-            allDescriptors.addAll(result);
+            Set<VariableDescriptor> oldValue = propertyDescriptors.putIfAbsent(name, result);
+            if (oldValue != null) return oldValue;
+
+            registerDescriptors(result);
         }
         return result;
     }
@@ -208,6 +219,16 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
         throw new UnsupportedOperationException(); // TODO
     }
 
+    protected void registerDescriptor(@NotNull DeclarationDescriptor descriptor) {
+        assert !allDescriptorsComputed : "getAllDescriptors() has been called already";
+        allDescriptors.add(descriptor);
+    }
+
+    protected void registerDescriptors(@NotNull Collection<? extends DeclarationDescriptor> descriptors) {
+        assert !allDescriptorsComputed : "getAllDescriptors() has been called already";
+        allDescriptors.addAll(descriptors);
+    }
+
     @NotNull
     @Override
     public Collection<DeclarationDescriptor> getAllDescriptors() {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyClassMemberScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyClassMemberScope.java
index f6e353d225b..a36d65ca9f9 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyClassMemberScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyClassMemberScope.java
@@ -16,7 +16,9 @@
 
 package org.jetbrains.jet.lang.resolve.lazy;
 
+import com.google.common.base.Optional;
 import com.google.common.collect.Lists;
+import com.intellij.openapi.util.Computable;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -64,8 +66,7 @@ public class LazyClassMemberScope extends AbstractLazyMemberScope<LazyClassDescr
         Collection<T> extract(@NotNull JetType extractFrom, @NotNull Name name);
     }
 
-    private ConstructorDescriptor primaryConstructor;
-    private boolean primaryConstructorResolved = false;
+    private final LazyValue<Optional<ConstructorDescriptor>> primaryConstructor;
 
     public LazyClassMemberScope(
             @NotNull ResolveSession resolveSession,
@@ -73,6 +74,12 @@ public class LazyClassMemberScope extends AbstractLazyMemberScope<LazyClassDescr
             @NotNull LazyClassDescriptor thisClass
     ) {
         super(resolveSession, declarationProvider, thisClass);
+        this.primaryConstructor = resolveSession.getStorageManager().createLazyValue(new Computable<Optional<ConstructorDescriptor>>() {
+            @Override
+            public Optional<ConstructorDescriptor> compute() {
+                return Optional.fromNullable(resolvePrimaryConstructor());
+            }
+        });
     }
 
     @NotNull
@@ -331,9 +338,12 @@ public class LazyClassMemberScope extends AbstractLazyMemberScope<LazyClassDescr
 
     @Nullable
     public ConstructorDescriptor getPrimaryConstructor() {
-        if (primaryConstructorResolved) {
-            return primaryConstructor;
-        }
+        return primaryConstructor.get().orNull();
+    }
+
+    @Nullable
+    private ConstructorDescriptor resolvePrimaryConstructor() {
+        ConstructorDescriptor primaryConstructor = null;
         if (GENERATE_CONSTRUCTORS_FOR.contains(thisDescriptor.getKind())) {
             JetClassOrObject classOrObject = declarationProvider.getOwnerInfo().getCorrespondingClassOrObject();
             if (!thisDescriptor.getKind().isObject()) {
@@ -353,7 +363,6 @@ public class LazyClassMemberScope extends AbstractLazyMemberScope<LazyClassDescr
                 primaryConstructor = constructor;
             }
         }
-        primaryConstructorResolved = true;
         return primaryConstructor;
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyPackageMemberScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyPackageMemberScope.java
index 4edbbb5067f..de6ef262591 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyPackageMemberScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LazyPackageMemberScope.java
@@ -16,7 +16,6 @@
 
 package org.jetbrains.jet.lang.resolve.lazy;
 
-import com.google.common.collect.Maps;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.psi.JetDeclaration;
@@ -26,23 +25,26 @@ import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
 
-import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentMap;
 
 public class LazyPackageMemberScope extends AbstractLazyMemberScope<NamespaceDescriptor, PackageMemberDeclarationProvider> {
 
-    private final Map<Name, NamespaceDescriptor> packageDescriptors = Maps.newHashMap();
+    private final ConcurrentMap<Name, NamespaceDescriptor> packageDescriptors;
 
     public LazyPackageMemberScope(@NotNull ResolveSession resolveSession,
             @NotNull PackageMemberDeclarationProvider declarationProvider,
             @NotNull NamespaceDescriptor thisPackage) {
         super(resolveSession, declarationProvider, thisPackage);
+
+        this.packageDescriptors = resolveSession.getStorageManager().createConcurrentMap();
     }
 
     @Override
     public NamespaceDescriptor getNamespace(@NotNull Name name) {
         NamespaceDescriptor known = packageDescriptors.get(name);
         if (known != null) return known;
+
         if (allDescriptorsComputed) return null;
 
         if (!declarationProvider.isPackageDeclared(name)) return null;
@@ -52,8 +54,10 @@ public class LazyPackageMemberScope extends AbstractLazyMemberScope<NamespaceDes
         assert packageMemberDeclarationProvider != null : "Package is declared, but declaration provider is not found: " + name;
         NamespaceDescriptor namespaceDescriptor = new LazyPackageDescriptor(thisDescriptor, name, resolveSession, packageMemberDeclarationProvider);
 
-        packageDescriptors.put(name, namespaceDescriptor);
-        allDescriptors.add(namespaceDescriptor);
+        NamespaceDescriptor oldValue = packageDescriptors.putIfAbsent(name, namespaceDescriptor);
+        if (oldValue != null) return oldValue;
+
+        registerDescriptor(namespaceDescriptor);
 
         return namespaceDescriptor;
     }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java
index 1fbd9b32cb3..393af7e09fb 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java
@@ -27,6 +27,7 @@ import org.jetbrains.jet.util.slicedmap.WritableSlice;
 
 import java.util.Collection;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.ConcurrentMap;
 
 public class LockBasedStorageManager implements StorageManager {
@@ -44,6 +45,11 @@ public class LockBasedStorageManager implements StorageManager {
         return new ConcurrentHashMap<K, V>();
     }
 
+    @Override
+    public <E> Collection<E> createConcurrentCollection() {
+        return new ConcurrentLinkedQueue<E>();
+    }
+
     @NotNull
     @Override
     public <T> LazyValue<T> createLazyValue(@NotNull Computable<T> computable) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java
index 6f553db0ecd..65d37686268 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java
@@ -20,12 +20,15 @@ import com.intellij.openapi.util.Computable;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.resolve.BindingTrace;
 
+import java.util.Collection;
 import java.util.concurrent.ConcurrentMap;
 
 public interface StorageManager {
     @NotNull
     <K, V> ConcurrentMap<K, V> createConcurrentMap();
 
+    <E> Collection<E> createConcurrentCollection();
+
     @NotNull
     <T> LazyValue<T> createLazyValue(@NotNull Computable<T> computable);