Hi, I've been experimenting with with some gcc options and features. What I found out so far is that with the options -fprofile-generate and - fprofile-use I was able to increase the Richards and pystone benchmark results (on top of pypy-c) with a little over 15%. Stackless is currently still 10-15% slower compared to plain vanilla PyPy, but I have some idea that I would like to look into in the next couple of days to make that better. cheers Eric