Hardware is an ATI Radeon 7000 on an AMD Sempron 3100+ with 512MB RAM. Linux kernel is 2.6.23.14 with x.org 1.4.0.90, OpenGL 1.3 on Mesa 7.0.1.
Gameplay - even the main menu at startup - is extremely slow, as though there is no GL driver running at all. The biggest problem is the mouse... the cursor movement usually lags behind the mouse movement by several seconds, and then suddenly shoots across the screen seemingly at random.
I thought there might be something wrong with the driver, so I installed the current flavor of tuxracer and that ol' penguin flies along chomping down his herring with no degradation in speed. glxgears returns an average fps of around 272 - not spectacular, but at least it works smoothly.
Turning off 3d textures made only the slightest bit of difference... at least now I can eventually get the mouse pointer to rest on the "Exit" option to shut down the game.
Does this sound like a stupid user error (likely), a known problem with that card, a driver error, something else I can fix?