We now have multiple customers where DWM.exe uses too much CPU randomly.
In our monitoring, we see spikes that DWM.exe uses 25% percent constant CPU (so 1 of the 4 cores in the VM) for a couple of hours, then it suddenly stops again.
When doing a CPU trace via Windows Performance Analyzer, we see that DWM.exe is using all this CPU via d3d10warp.dll.
It's happening in connected and also in disconnected sessions. Connecting / disconnecting does not seem to trigger it or stop it. We tried using a different VM size (Intel / AMD CPU), no effect. When the user logs off and logs on a again, problem seems to be fixed for a random period of time.
It seems to happen to some particular users most of the time (but sometimes also to random users once). We contacted these most-reported users, but they have no "special" client machines like 200% DPI, 4K displays, non-Windows clients, dark theme enabled etc. Just default settings, maximum 2x full HD monitor.
It also happened once to an administrator RDP session (connected via classic RDP, not via WVD).
Does anyone else have this problem? It seems our customers who are still running WVD Windows 10 v1903 are not experiencing this.