AMD has been paying developers for years to develop free drivers. It has taken this long because they essentially had to rewrite everything and modern display drivers are complicated beasts.
The in-kernel, fancy KMS, AMD drivers should just work right now for many people. 2D is faster than the proprietary driver and the 3D speed is a significant fraction of the proprietary driver.
Have you tried enabling dpm? When enabled with a kernel parameter it dynamically changes the card frequency. I think you need a kernel version > 3.11. Check out:
I didn't yet. The best results I could possibly achieve were dynpm ones - about 65 degrees Celsius, which is completely unacceptable anyway. I've moved to a regular desktop PC, and I'm so happy for it ever since. Good to know though, that some improvement seems to be made. Thanks for that link!
The in-kernel, fancy KMS, AMD drivers should just work right now for many people. 2D is faster than the proprietary driver and the 3D speed is a significant fraction of the proprietary driver.