Moving from 5.9.3 to 5.10.0, I noticed that my CPU usage goes from around 25% when active or idle on 5.9.3, to 95% when active and 120% when idle on 5.10.0. I am running with OnDemand rendering. I do not see large changes when running Always.
I have run some profiling in Instruments, 10 seconds of each qt version, and have attached the screenshots below where I see very different behavior. Even specifying OnDemand I see that in 5.10.0 it is often calling performDraw when it does not in 5.9.3. Perhaps the problem is linked to ignoring OnDemand?
I notice similar CPU usage increases when running the examples with OnDemand rendering. When running with the simple-qml example my CPU usage goes up to 229% when idle.