^^there is a way to get MotB onto the Mac NWN2 here.
Performance is pretty dire on an X1600, I'm amazed you didn't go insane Brad, I have to run it with pretty much all settings on minimum.
In my defense, I left Aspyr for Apple right about the time we entered beta on NWN2, so perhaps something went horribly wrong afterwards?
I know that during development, one of the key areas of performance degradation was shadow support. NWN2 uses some advanced D3D techniques that we couldn't easily do on the Mac without sending performance in the toilet.