The problem put simply is when running the 3DS emulator Citra on an AMD GPU it gives me 3-5 pfs knowing that the 3DS games are not demanding there have to be a problem with the OpenGL drivers.
Same problem comes to play when running the Wii U emulator CemU the AMD GPUs have slow down issues and are very laggy when running demanding game like the legend of zelda.
*Have to point out that Both these emulators Runs Perfectly fine with Nvidia users with medium GPUs but Prowerful AMD GPUs face them, so the problem is definitely the AMD GPUs/Drivers
Also Some users use linux with custom AMD drivers and they don't get these problems, and everything runs good.
I think you should try running those emulators to give an idea of exactely what the problem is and hopefully fix it.