I was going to submit a new bug report, but I suspect this is =
the same issue.

I recently purchased an i7 7700 + Radeon RX 560 2GB to replace my older i5 =
4650
+ Radeon HD 7770.
But I noticed performance on Dolphin Emulator *went down*. Way down when us=
ing
OpenGL; whereas Vulkan has no performance issues and running on Windows giv=
es
similar performance to Linux with Vulkan.

But what's more baffling is the performance with our Ogre 2.1 samples:
1. If I run our Postprocessing sample I can easily obtain 500 fps.
2. But if certain processes are running on the background, such as RenderDoc
with a capture (even if RenderDoc is minimized), the framerate will go down=
 as
low as 55-69fps; with CPU usage around 3% and radeontop indicating a GPU us=
age
of 15%. This behavior is a little inconsistent, as closing RenderDoc will
increase performance back to 500 fps, but opening RenderDoc again will keep=
 it
at 500 fps. RenderDoc is not the only process to induce this mysterious
behavior, but it is the one I've managed to identify correctly.

At first I suspected a clocking problem, but after setting CPU governor to
performance and echo high >
/sys/class/drm/card0/device/power_dpm_force_performance_level the problem
persisted.

The framerate drops aren't also consistent, another of our samples for exam=
ple
reduces their performance from 200fps to 40fps.
Dolphin should be performing between 100-200 fps (by comparing with Vulkan =
and
Windows versions) but it manages between 21-49fps

I will try to see if older versions of Mesa as this ticket suggests will so=
lve
the problem; although I'm not sure if Mesa 17.0.0 supports Polaris.