Low perfomance with SW rendering using QOpenGLWidget showing content on VNCViewer

Since QGLWidget has become obsolete the user replaced it with QOpenGLWidget in her application. Now she is facing the performance issue using SW rendering. The user is running her application using VNC Viewer. While using QGLWidget the processor time used is more or less in acceptable range. With QOpenGLWidget the processor time used can get higher than 80%.

The expected behaviour is of course normal processor usage with QOPenGLWidget as it was in QGLWidget (see the glwidget.avi video).

What actually happens can be seen on qopenglwidget.avi video.

You can see the difference in performance on videos attached. Note, there is no any visible or invisible elements on the widget. Only Black static screen is displayed.

This should be reproducible with the application attached.

Steps to reproduce:
1. Run the application
2. Open one of the menu and move mouse pointer to another. Observe, the application is not getting slow.
3. From file select Create QGLWidget.
4. Do everything as described in step two. Observe, it still works as it suppose to do
5. From file select Create QOpenGLWidget.
6. Do everything as described in step two. Observe the processor usage is getting higher then 80%

This should be done through the VNC Viewer. Platform: X11 Windows