In some cases, Pypy performs worse than CPython when running Krakatau, and it has gotten a lot worse from 2.3 to 2.5
You can run it with pypy Krakatau\benchmark.py -path <path to Java rt.jar>
I get the following timings
CPython: 17.43s
Pypy 2.3: 38.48s (build pypy-c-jit-71056-c8e3b8cbc843-win32)
Pypy 2.4: 39.92s (build pypy-c-jit-72200-375133966c12-win32)
Pypy 2.5: 49.94s (build pypy-c-jit-74404-9fd586fe0fe5-win32)
Not only was it slower than CPython to begin with, but it got much worse recently.