I just noticed something interesting. Someone in this thread mentioned that performance improves when rebooting from Windows into DOS mode. I have tested it:
Vquake, booted straight into DOS: 20.3 fps
Vquake, rebooted into DOS mode: 22.0 fps
I then found out that the "dmatest.exe" tool ran from normal DOS says that bus mastering is disabled and DMA mode will not work. But when rebooted into DOS mode, it suddenly says DMA is enabled. I then benchmarked vquake with the "-nodma" switch, and performance drops again from 22.0 to 20.3 fps.
I had noticed this before when I booted into DOS mode and some games felt a bit smoother, but I thought it was just placebo. Turns out that it really does improve performance, in this case by working around a bug that seems to prevent enabling DMA mode.
And what's weird is that the dmatest benchmark gives me:
"FIFO performance 11.4 MB/s"
"DMA performance 10.4 MB/s"
Shouldn't that mean "vquake -nodma" is faster? But according to the timedemo benchmark, DMA mode wins.
And finally, when I run vquake or dmatest from a Windows 95 dos box, they both crash with a page fault exception, and a few seconds later, the computer freezes with a black screen.