Installed Stackless Python and played around a bit.

uxPython currently uses 4 threads - one is the main program and three python threads to service events in the event queue. More can be created in case any of the threads block. I replaced some threading and some "physics" code that ran in the main thread with Stackless tasks and saw no gain or loss in framerate. My program is rendering limited so that is to be expected. In the past when it was using most of it's time locking/releasing stackless would have been awesome.

Another drawback is that Psyco does not work with Stackless, Psyco gives about 20% more performance while Stackless gives about 0% more in my test case.

Conclusion: Stackless is great for what it is designed for BUT if you don't have many threads and scheduling problems it won't provide any value.