Emulator

Game Name?
Any

Game ID?
Any

What's the problem? Describe what went wrong in few words.

Before 4.0-1778, the OpenGL Plugin was the fastest for AMD cards.
After 4.0-1778 however, the OpenGL plugin was slown down to half of it's performance before 4.0-1778.

What did you expect to happen instead?

Performance from 4.0-1776.

What steps will reproduce the problem?
[Don't assume we have ever played the game and know any level names. Be as
specific as possible.]

1. Own an AMD card
2. Use latest driver
3. Try to use the OpenGL plugin, you'll notice it's way slower than D3D

Dolphin 3.5 and 3.5-367 are old versions of Dolphin that have
known issues and bugs, so don't report issues about them and test the
latest Dolphin version first.
Which versions of Dolphin did you test on?

4.0-1776 and 4.0-1778

Does using an older version of Dolphin solve your issue? If yes, which
versions of Dolphin used to work?

Anything before 4.0-1778

What are your PC specifications? (including, but not limited to: Operating
System, CPU and GPU)

Intel Core i5 4670k @4.4Ghz
ASUS AMD HD7970
Corsair Vengeance 8GB RAM
MSI Z87 G45 Motherboard
Windows 8.1 64-bit

Are you using the 32 or the 64 bit version of Dolphin?

64-bit (shouldn't this question be removed :P)

Is there any other relevant information? (e.g. logs, screenshots,
configuration files)

While this does speedup nvidia cards, it reduces AMD cards to half the performance.