AMD’s last two Radeon drivers have included optimizations for DOOM. Last weeks drivers did not really give us any specific numbers, but this weeks drivers (Radeon 22.214.171.124) according to AMD will give you a performance boost up to 35% on a R9 390 over the previous drivers. That is definitely a nice increase!
If you are running an AMD R9 390 or even older cards like the R9 290 series it is probably a good idea to get the latest drivers as you will see a definite performance increase in DOOM.
Download the latest AMD drivers here.