AMD To Drop Radeon HD 2000/3000/4000 Catalyst Support
Tweaking the open-source Radeon driver configuration led to the Xonotic low-quality frame-rates on the Radeon HD 4770 going up by 11%, but the Catalyst driver was more than twice as fast for this game.
Running Xonotic with high quality settings at the HD resolution led to not-really-playable frame-rates for the HD 4770 on open-source. The open-source driver performance is moving in the right direction with the Git code being about 9% faster and an additional 8% can be squeezed out of tweaking the driver (PCI Express 2.0 + 2D color tiling), but overall the Radeon Gallium3D driver is only running at 38% the speed of Catalyst for this game.