The Nexuiz 2.5.2 release would not run on pre-2008 Linux drivers or with the drivers under Ubuntu 8.10, but when comparing the Gallium3D stack from today to the Catalyst 8.3 driver from 2008, the outdated binary blob is nearly twice as fast.
When running Nexuiz at 800 x 600, the Catalyst 8.3 driver still reigns supreme over the modern Gallium3D R300 driver.
The Warsow game performance is not playable at 1400 x 1080 (the native LVDS resolution of the ThinkPad R52) with the Mobility Radeon X300 under Ubuntu Linux. However, the frame-rate of Warsow does go up greatly with the post-2007 Catalyst drivers. The Catalyst 9.3 release with Warsow is more than twice as fast as the ATI/AMD Linux driver in Ubuntu 11.10. The latest Linux 3.2 / Mesa 8.0 configuration causes a performance regression too, which puts it slower than the fglrx 8.25 driver from 2006.
Warsow at 800 x 600 regresses hard between Linux 3.0 / Mesa 7.11 and Linux 3.2 / Mesa 8.0 with it losing more than half its frame-rate for the ATI Mobility Radeon X300. Regardless of this still-current regression in the open-source stack, even with Linux 3.0 / Mesa 7.11 graphics the Catalyst 9.3 driver was almost 2.5x faster.