I plan to post performance results on this page. According to some initial tests on my home PC (PIII 866, GeForce2 Ultra), the engine runs at about 90% of the speed of the real Q3A engine on the same machine! Of course, certain platforms (such as SGI) do not have multi-texturing. Without multi-texturing, it runs significantly slower. In our CAVE at NCSA (4 walls, 4 IR2s), it runs at around 24 fps in stereo, 48 in mono.
SGI Octane Users: your Octane may not have enough texture memory. For instance, the Octane MXE only has 4 MB. For better performance, run with an lodbias of 1 (textures scaled down to half size):
cq3a --lodbias 1