Author really needs to put the assembly under a profiler. Others have mentioned things like poor instruction selection (loop). In my experience it's good to fi

Author really needs to put the assembly under a profiler. Others have mentioned things like poor instruction selection (loop). In my experience it's good to first attempt a rewrite in C using intrinsics. This gets you thinking about data and register layout at a high level and let's you better identify mid level optimizations before committing to assembly.