This is a significant improvement. I knew there would be something to do with bitwise operators, but I was not versed enough to come up with such a solution.

This is giving the following benchmarks:

             Rate      orig  blokchop browserUK
orig       1178/s        --      -69%      -94%
blokchop   3829/s      225%        --      -81%
browserUK 20097/s     1606%      425%        --
[download]

In my testing, this is improving about 17x on my original, and about 5x on blokhead's chop based solution.

Thanks for the excellent suggestion,
-a