I thought there might be some people here who'd be interested in this graph: http://stromberg.dnsalias.org/~dstromberg/backshift/ It shows pypy performing very well when compared to a number of other Python runtime systems, including cpython+cython (2 and 3) and cpython+psyco (just 2 of course). It's just one part (the critical section) of one application, but still...