Uncertain if Apple have updated drivers along the way, recently revisited Doom 3 as had some time to burn, 2015 1.2 rMB running D3 @ 1440 x 900, ultimate settings mid to high 50`s FPS, occasionally dips to the mid 30`s. Last time I remember trying D3 it played much slower the point the game was not really playable due to the frame-rate.
nb. OS X 10.10.5
Q-6
nb. OS X 10.10.5
Q-6