diff -up webkitgtk-2.8.0/Source/JavaScriptCore/heap/CopiedBlock.h.page_size_align webkitgtk-2.8.0/Source/JavaScriptCore/heap/CopiedBlock.h
--- webkitgtk-2.8.0/Source/JavaScriptCore/heap/CopiedBlock.h.page_size_align	2015-03-23 09:08:04.000000000 +0100
+++ webkitgtk-2.8.0/Source/JavaScriptCore/heap/CopiedBlock.h	2015-04-08 12:02:51.218138924 +0200
@@ -79,7 +79,7 @@ public:
     size_t size();
     size_t capacity();
 
-    static const size_t blockSize = 32 * KB;
+    static const size_t blockSize = 64 * KB;
 
     bool hasWorkList();
     CopyWorkList& workList();
diff -up webkitgtk-2.8.0/Source/JavaScriptCore/interpreter/JSStack.cpp.page_size_align webkitgtk-2.8.0/Source/JavaScriptCore/interpreter/JSStack.cpp
--- webkitgtk-2.8.0/Source/JavaScriptCore/interpreter/JSStack.cpp.page_size_align	2015-04-08 12:02:51.218138924 +0200
+++ webkitgtk-2.8.0/Source/JavaScriptCore/interpreter/JSStack.cpp	2015-04-08 12:04:48.158143620 +0200
@@ -58,7 +58,8 @@ JSStack::JSStack(VM& vm)
     size_t capacity = Options::maxPerThreadStackUsage();
     ASSERT(capacity && isPageAligned(capacity));
 
-    m_reservation = PageReservation::reserve(WTF::roundUpToMultipleOf(commitSize, capacity), OSAllocator::JSVMStackPages);
+    size_t commitsize = pageSize();
+    m_reservation = PageReservation::reserve(WTF::roundUpToMultipleOf(commitsize, capacity), OSAllocator::JSVMStackPages);
     setStackLimit(highAddress());
     m_commitTop = highAddress();
     
@@ -92,7 +93,8 @@ bool JSStack::growSlowCase(Register* new
     // have it is still within our budget. If not, we'll fail to grow and
     // return false.
     ptrdiff_t delta = reinterpret_cast<char*>(m_commitTop) - reinterpret_cast<char*>(newTopOfStackWithReservedZone);
-    delta = WTF::roundUpToMultipleOf(commitSize, delta);
+    size_t commitsize = pageSize();
+    delta = WTF::roundUpToMultipleOf(commitsize, delta);
     Register* newCommitTop = m_commitTop - (delta / sizeof(Register));
     if (newCommitTop < reservationTop())
         return false;