AMD64 still slower than 32-bit x86 in Unreal

AMD64 still slower than 32-bit x86 in Unreal

Unreal Engine developers have so far been unable to bring the 64-bit version up to the same performance level as the 32-bit version, and no 64-bit-specific image quality improvements have been made:

http://www.amdzone.com/modules.php?op=modload&name=News&file=article&sid=1354&mode=thread&order=0&thold=0