During idle time the clock speed of my vega drops (according to WattMan and hwi) to 50-150Mhz and the system begins to lag extremely. Especially music and video playback begin to stutter and get worse in case of mouse/keyboard input. The only way to prevent that is to play a HD video or starting a game in the background, then the clock rate peaks to max and everything is fine.
I tried out several different drivers between 17.9 and 18.5.1, for some higher clock rates can be triggered more easily but the problem is there regardless of the version.
Did someone experience similar problems?