First I'm glad Witcher 2 is available on Mac, but:
Which mac is supposed to run this!?
I have already finished the game in Windows 7, I ran with high settings with AA with and FPS from 50-60 FPS never dipping below 40 FPS.
The same machine is not capable of maintaining 20 FPS on lowest settings in Mac OSX!
Also the port totally locks down the system while running. You cannot minimize game or even tab out! If skype calls or I have to check my mail I have to shut down the game!
I have a NVidia GTX285 1024MB (this card is 50% faster than the recommended GT650M)
I also run on a Vertex 3 SSD and have 16GB RAM and I'm on Mountain Lion.
Attaching OpenGL profiler shows the game runs at around 15-20FPS, my graphics card is maxed (90-100% utilization) and i use a mere 30% of my CPU power, not even maxing one core. GPU memory usage goes from about 600-650MB.
I would suspect lower performance in OSX, no doubt, but going from 60 FPS on high settings to 15-20FPS on low settings is not what i expected.
Unless there is some driver issues with my specific card, then this port is 100% broken. The game runs better in wine.
Note, i'm not tossing out numbers here, the FPS on win7 was measured with EVGA precision and i used OpenGL profiler from XCode to measure performance on Mac OSX.