You aren't using anything special in your command line are you? One thing I suppose would be worth trying is seeing what happens when you use some of the memory/video tweaking command line options.
Give -lowmem or -superlowmem a try, and see if it improves. Otherwise try -himem -highvidmem -nomultitexture and -nocompress to see if any of them help.
(19:11) [D3k]Gooberman: pffft, I didnt get owned baal, you just got 60 lucky fusion shots