My research regarding NVidia Optimus resulted in finding out one's either lucky and has an option in the BIOS to disable it (I don't) or else there is no way to get rid of it, as the graphics card needs to pipe frames through the Intel HD component (or something along those lines - it got too technical for me).

I tried doing something simple as throwing 5 instances of MyQGLWidget into a QHBoxLayout, as well as into a QSplitter, both resulting in a horrendous lagfest, where every widget gets repainted one frame later than the other, regardless of whether I use GPU/Intel HD. This would mean ridiculous performance once I made a proper application from these. I then tried using traditional QWidgets using QPainter and paintEvent, which works pretty much flawlessly with either graphics component. If I just turn these into QGLWidgets again, I am back to horrible performance.

Bottom line: QWidget probably has enough performance for the simple thing I plan to do, anyway. I just cannot use GLWidgets if they're going to be unreliable, and I don't even think an NVidia Optimus-infested system such as mine already represents the worst possible target machine.

Thanks for your efforts.