The OS X build is looking good. On my G4 dual 800 with a GeForce 3 card I get 90fps in game, while on my P3 dual 800 with a GeForce 3 I get 30fps on the same settings.
I've been running it on my machine without problem, in game and out. However, I'm using a developer build of 10.1 (5G48), and I've not tested across anything else. I'll continue to do that tomorrow before putting out a general public release.
Meanwhile, if you want to play the BLEEDING edge client, you can grab it from my iTools public folder (graemedevine). You'll need to have downloaded and installed a full PC build because this is just the app, so this limits the # of you that can play it to experts and desperate types.. I've been updating the build here for people to test on since I only have a few OS X machines here to play with.
Please ONLY send bug reports on this build to me at firstname.lastname@example.org and try to include a clear step by step way to replicate the error you have. Please also include the OS X build you have running and what kind of video card you have installed.