Each call to QOpenGLContext::makeCurrent calls NSOpenGLContext::update which impacts performances a lot in my case.

This "update" call is necessary when the Window surface geometry changed or when display mode changed. It would be good to avoid this call when not required.

I have 7 OpenGL widgets, at 60 FPS, that's 7*60 calls per second.
In Instruments I can see the application spends 10% time in this call and 0.2% in NSOpenGLContext::makeCurrentContext:

188.00 ms   11.2%    1.00 ms                                   QOpenGLContext::makeCurrent(QSurface*)
184.00 ms   10.9%    0 s                                    0x11db03470
173.00 ms   10.3%    0 s                                     -[NSOpenGLContext update]
5.00 ms    0.2%    0 s                                     -[NSOpenGLContext makeCurrentContext]