If you have a non 64bit Debian machine (like a duron, p3 etc) installing libc6-i686 will speed it up.
# note that doing this you may need to restart running programs otherwise they might crash.
# rebooting might be an idea, if you do not know how to restart all your programs.
apt-get install libc6-i686
After I had it installed I got a 7% faster pystone result. I also got a couple of fps quicker in some pygames. This was with an AMD duron 850mhz system, your milage may vary.