With long-running qt applications which have much animations (like refgui app in ic-eg's cluster demo), it becomes very sluggish due to a timer leak issue which already have been reported to the qt project:

https://bugreports.qt.io/browse/QTBUG-79838

Although I've confirmed that the patch attached to the ticket works fine, the ticket is still open since non-commercial version of qt 5.x is no longer maintained.

Since this seems not to be AGL-specific issue, it would be preferable to upstream this fix to openembedded's meta-qt5 repository.

Proposal patch for meta-qt5 is attached.