[Bug 206231] R9 280X low performance with all games

[sylvain.bertrand at gmail.com]

Dirt Rally is a GL game, not a vulkan game.

It happens I have it in my library even though I don't recall to buy
it.

Anyway I did run the included benchmark:
  - cpu governor to performance
  - monitor refresh rate 144Hz
  - 1920x1080
  - 8xmsaa
  - _no_ vsync
  - everything to max

avg fps: ~48fps
low fps: ~30fps
max fps: ~60fps

I get several GPU vm faults in dmesg too, but no crash (like in vulkan "rise of
the tomb raider").

-- 
Sylvain