Go back to doubling the size when growing new space....

src/spaces.cc

 // Copyright 2006-2008 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 1061 matching lines @@
 }
 
 
 void SemiSpace::TearDown() {
   start_ = NULL;
   capacity_ = 0;
 }
 
 
 bool SemiSpace::Grow() {
-  // Commit 50% extra space but only up to maximum capacity.
+  // Double the semispace size but only up to maximum capacity.
   int maximum_extra = maximum_capacity_ - capacity_;
-  int extra = Min(RoundUp(capacity_ / 2, OS::AllocateAlignment()),
+  int extra = Min(RoundUp(capacity_, OS::AllocateAlignment()),
                   maximum_extra);
   if (!MemoryAllocator::CommitBlock(high(), extra, executable())) {
     return false;
   }
   capacity_ += extra;
   return true;
 }
 
 
 #ifdef DEBUG
@@ skipping 1506 matching lines @@
                      reinterpret_cast<Object**>(object->address()
                                                 + Page::kObjectAreaSize),
                      allocation_top);
       PrintF("\n");
     }
   }
 }
 #endif  // DEBUG
 
 } }  // namespace v8::internal