We're doing the final work now to replace CoreLoop with TransportLoop, WindowLoop, and SceneLoop. All three are instances of soy._internals.LoopThread which (should) play well with Python's threading system and should never hold the GIL.
The increased performance this has brought for multi-core users is amazing, some have reported more than twice the framerate!
To be fair, an equal number of subversion Trunk users are experiencing frequent segfaults since we've not finished adding mutexes and rearranging the internal API post-move. Obviously these issues are being resolved prior to the Beta-3 release next month.