LinuxHardware.org has posted a performance analysis of DOOM 3 on a Linux box with four NVIDIA cards: GeForce 3, GeForce 4 Ti 4600, GeForce FX 5900 Ultra, and a GeForce 6800GT; the OS utilized for comparison is Windows XP. LinuxHardware.org also received some clarification from id Software’s Timothee Besset on their results:
You’ll probably notice that on Linux Doom III will be more CPU bound than card bound. I can see several factors, mostly the fact that the SSE2 code is not used in the current binary, and maybe because gcc doesn’t optimize as well as VC.net does. I will be spending some time in the upcoming months optimizing the builds for more speed. I don’t expect to get more than a 5-10% fps gain though.