I tried this test on parrotbench (b0.py in particular) and I'm not sure I could distinguish an improvement over the noise (best case was about 5%).  The variability is pretty high on my box (dual amd64 opertons, ubuntu gcc 4.1.2-ish).  At first it seemed a bit slower with the original patch which uses unsigned ints.  I tried changing to unsigned longs.  It seemed a little better, though not sure if it was really due to the change.  I think unsigned longs should be used for 64-bit boxes.

Did you use a benchmark/program that is open source?  I don't know that I have anything decent to test this with.  Raymond probably does though.  Also what platform did you test on?