Intel OpenGL Performance: OS X vs. Windows vs. Linux
When running Warsow 1.0, the Ubuntu Linux OpenGL testing revealed performance improvements when moving to the newer code, which now puts it at parity with the OS X 10.8 performance for this first person shooter powered by the Qfusion engine.
With X-Plane 9, for the flight simulator on OS X its performance was noticeably better than Linux -- Mountain Lion delivered about 20% better performance.