Increase the size of the max object that can be new space allocated....

src/heap.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1101 matching lines @@
   // scavenge since last new space expansion.
   static int survived_since_last_expansion_;
 
   static int always_allocate_scope_depth_;
   static int linear_allocation_scope_depth_;
 
   // For keeping track of context disposals.
   static int contexts_disposed_;
 
 #if defined(V8_TARGET_ARCH_X64)
+  static const int kMaxObjectSizeInNewSpace = 1024*KB;
+#else
   static const int kMaxObjectSizeInNewSpace = 512*KB;
-#else
-  static const int kMaxObjectSizeInNewSpace = 256*KB;
 #endif
 
   static NewSpace new_space_;
   static OldSpace* old_pointer_space_;
   static OldSpace* old_data_space_;
   static OldSpace* code_space_;
   static MapSpace* map_space_;
   static CellSpace* cell_space_;
   static LargeObjectSpace* lo_space_;
   static HeapState gc_state_;
@@ skipping 970 matching lines @@
   // Return whether this object should be retained. If NULL is returned the
   // object has no references. Otherwise the address of the retained object
   // should be returned as in some GC situations the object has been moved.
   virtual Object* RetainAs(Object* object) = 0;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_