doktor83 in one of the recent patches you disabled the restart gpu on startup option for all gpus except Vega, but it is also required for the R9 Fury.

I have found that if I do anything on my pc that requires GPU access (editing, 3d and games) after I am done, if i start the miner up again my hash rate is ~30% lower, but if i disable the GPU and re-enable it, hash rate returns to full speed.