QEvent::UpdateRequest is too slow

hexo

I have a QWidgets (C++) android application (qt 6.4.3). I am trying to optimize it to work smoothly on 120hz phones, but I have noticed the QEvent::UpdateRequest of the main widget is taking about 14ms on my phone which makes it impossible to achieve 120hz. The app only has a handful of simple widgets (buttons, text area, etc.) and a single custom QOpenGLWidget. I have timed the paintGL of this widget and it takes less than 1ms.

My question is, is there any way to optimize UpdateRequest speed? And do you have any pointers on what the culprit of this poor performance might be?

SGaist

Hi and welcome to devnet,

Widgets are CPU rendered hence the performance you see. If you want OpenGL backed rendering of your buttons then you should move to QtQuick.

hexo

Thanks, but shouldn't even the CPU rendering be faster? I only have 2-3 widgets, not a lot.

SGaist

The widgets module is not optimized for mobile so there might be other issues at hand.

hexo

Just changing the root widget of my application from QWidget to QQuickWidget fixed the problem. Well, that was way easier than I expected! Thanks for the help.