hi,
when i run Diablo 3 on my AN515-42 the game somehow limits the CPU at 1600MHz
its not thermal throttled (under 50°C)
other games work fine (like “The Division” or “Dying Light”)
its not TDP bound - as i raised TDP to 30W; and run dGPU
the game triggers the battery power saving mode…
did so - but its more likely a Bug and not a user-error (as i usually know what i am doing) 
kind of “fixes” when using 32-bit client - now CPU boosts to 2400MHz
BUT should boost to 3600MHz with my Laptop
edit:
Acer Nitro 5 AN515-42 is plugged in; battery fully charged; “AMD Ryzen Balanced” Powerplan; uses dGPU; Game is set to “high performance” in Win10 Graphics Settings; APU is running at 30W TDP (with RyzenAdj)
so i think its definitly a bug
also its not the AMD driver - as my Desktop with Ryzen and Polaris GPU work fine and as intended