IIRC when you want to mix both, you need to enclose your OpenGL primitives call between painter-> beginNativePainting() and painter->endNativePainting()
Thank you for your answere. I've already tried that but it wasn't the solution. I've figured out that the problem occures when turning on OpenGL rendering. I guess it has to do with my hibryd graphic system. My main card has some serious problems so I can't run Optirun right now and I guess my secondary GPU does not support the required features (only OpenGL 3.X).
I'm not shure about that but as I said: turning off the OpenGL rendering solved that problem for me. Maybe it helps others.
@zepfan As told earlier the rendering is all done by OpenGL which in turn is handled by the GPU so that wont matter. The Timer is what is affecting the CPU.
QtQuick renderer is capable of handling thousands of items at a time. Please check it here. Also here are some benchmark examples.
Extremetable example loads 100000 items as and when required.
Anyway here are some more link that you may fine useful:
http://doc.qt.io/qt-5/qtquick-performance.html
http://www.sletta.org/apps/blog/show/42708211-looking-at-throughput-in-qt-quick
http://doc.qt.io/qt-5/qtquick-visualcanvas-scenegraph-renderer.html
Try profiling your example.
