Quake was notorious for being the first major game to require a powerful FPU. Michael Abrash manually tuned the rasterization code to fit the Pentium pipeline, any other CPU didn't cut it.
Every room with torches was max 9FPS on 320x200 on DX2 OCed to 3x50MHz, literally 50% performance over your PC. Turnig off all objects through console made torches vanished and FPS doubled.