https://bugs.freedesktop.org/show_bug.cgi?id=97260
--- Comment #2 from Jan Ziak 0xe2.0x9a.0x9b@gmail.com --- Just a note:
I am not experiencing such a performance regression on R9 390 with kernel 4.7.0 - 4.8.0-rc1, amdgpu.ko kernel module, Gentoo Linux.