When starting off with Doom 3 and running it at 1920 x 1080 with low-quality effects, this eight year old game can't even push out more than 30 frames per second on the latest open-source stack even when it's tweaked for performance. Meanwhile, the proprietary Catalyst driver is about six times faster on the Radeon HD 4770 with an average frame-rate of about 180 FPS.
With Lightsmark, the OpenGL lighting benchmarking, the latest open-source Radeon driver also continues to be slaughtered by Catalyst when it comes to performance. Lightsmark is about seven times faster with Catalyst on this four-year-old Radeon hardware. As a consolation prize, at least when moving from the Ubuntu 12.04 LTS packages to the latest Radeon Git with tweaks the performance goes improve by 11%, but it will not be at parity with the proprietary Catalyst driver in the foreseeable future.
When running the defunct open-source Nexuiz game on the Radeon HD 4770, the proprietary Catalyst driver at 1920 x 1080 is twice as fast with a frame-rate of over 100 FPS while the open-source stack is below 50 FPS. The default open-source Radeon driver in Ubuntu 12.04 LTS is pushing out just 41 FPS while this goes up to 45 FPS (+9%) with the latest Mesa/kernel/libdrm/xf86-video-ati Git code and then up to nearly 49 FPS when enabling PCI Express 2.0 and 2D color tiling.