diff --git a/src/heap.cc b/src/heap.cc
index f8d22a2e36..aa7a5c7139 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -277,7 +277,9 @@ void Heap::GarbageCollectionPrologue() {
 int Heap::SizeOfObjects() {
   int total = 0;
   AllSpaces spaces;
-  while (Space* space = spaces.next()) total += space->Size();
+  while (Space* space = spaces.next()) {
+    total += space->Size();
+  }
   return total;
 }
 
diff --git a/src/math.js b/src/math.js
index db75cb28ae..91bf206a8b 100644
--- a/src/math.js
+++ b/src/math.js
@@ -184,6 +184,7 @@ function MathTan(x) {
 function SetupMath() {
   // Setup math constants.
   // ECMA-262, section 15.8.1.1.
+  %OptimizeObjectForAddingMultipleProperties($Math, 26);
   %SetProperty($Math,
                "E",
                2.7182818284590452354,
diff --git a/src/runtime.cc b/src/runtime.cc
index 0da4be8216..5518d15529 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1022,6 +1022,30 @@ static Object* Runtime_InitializeConstContextSlot(Arguments args) {
 }
 
 
+static Object* Runtime_OptimizeObjectForAddingMultipleProperties(
+    Arguments args) {
+  HandleScope scope;
+  ASSERT(args.length() == 2);
+  CONVERT_ARG_CHECKED(JSObject, object, 0);
+  CONVERT_SMI_CHECKED(properties, args[1]);
+  if (object->HasFastProperties()) {
+    NormalizeProperties(object, KEEP_INOBJECT_PROPERTIES, properties);
+  }
+  return *object;
+}
+
+
+static Object* Runtime_TransformToFastProperties(Arguments args) {
+  HandleScope scope;
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(JSObject, object, 0);
+  if (!object->HasFastProperties() && !object->IsGlobalObject()) {
+    TransformToFastProperties(object, 0);
+  }
+  return *object;
+}
+
+
 static Object* Runtime_RegExpExec(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 4);
diff --git a/src/runtime.h b/src/runtime.h
index cdf21dcabf..d47ca18e79 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -247,6 +247,8 @@ namespace internal {
   F(InitializeVarGlobal, -1 /* 1 or 2 */) \
   F(InitializeConstGlobal, 2) \
   F(InitializeConstContextSlot, 3) \
+  F(OptimizeObjectForAddingMultipleProperties, 2) \
+  F(TransformToFastProperties, 1) \
   \
   /* Debugging */ \
   F(DebugPrint, 1) \
diff --git a/src/spaces.h b/src/spaces.h
index 4760a42402..15f0628476 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -1574,7 +1574,7 @@ class FixedSpace : public PagedSpace {
   // Give a fixed sized block of memory to the space's free list.
   void Free(Address start) {
     free_list_.Free(start);
-    accounting_stats_.DeallocateBytes(Map::kSize);
+    accounting_stats_.DeallocateBytes(object_size_in_bytes_);
   }
 
   // Prepares for a mark-compact GC.
diff --git a/src/v8natives.js b/src/v8natives.js
index 841c920852..605df4920d 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -46,12 +46,16 @@ const $isFinite = GlobalIsFinite;
 
 // Helper function used to install functions on objects.
 function InstallFunctions(object, attributes, functions) {
+  if (functions.length >= 8) {
+    %OptimizeObjectForAddingMultipleProperties(object, functions.length >> 1);
+  }
   for (var i = 0; i < functions.length; i += 2) {
     var key = functions[i];
     var f = functions[i + 1];
     %FunctionSetName(f, key);
     %SetProperty(object, key, f, attributes);
   }
+  %TransformToFastProperties(object);
 }
 
 // Emulates JSC by installing functions on a hidden prototype that
@@ -454,8 +458,10 @@ function NumberToJSON(key) {
 
 function SetupNumber() {
   // Setup the constructor property on the Number prototype object.
+  %OptimizeObjectForAddingMultipleProperties($Number.prototype, 8);
   %SetProperty($Number.prototype, "constructor", $Number, DONT_ENUM);
 
+  %OptimizeObjectForAddingMultipleProperties($Number, 5);
   // ECMA-262 section 15.7.3.1.
   %SetProperty($Number,
                "MAX_VALUE",