Hi again.
Unfortunately i have nothing done in QML yet and only little with python, so i will be no direct help. But i suggest to look at the parts in your code where session/state/property/size-changes occur and watch their values.
Its crashing 100/100 when in background, mostly within 10-50 seconds.

The reason i asked about the thumnails/memory. i deleted all thumnails, when opening MPGQ they get created. When restarting there seems to be no performance gain. So why are they saved at all? Maybe they get created at every start? What it will be, there is room for improvement

Oh, i have to get back to work ^^