I have rather strange problem. There is a QOpenGLWidget set as viewport for QGraphicsView. But the CPU load more than without QOpenGLWidget. Even if there isn't anything in scene. When you using deprecated QGLWidget the CPU load is normal.

Profiler shows that for the main part of cpu load is responsible the follow function:
convertRGBA8888FromARGB32PM_sse4(unsigned int*, unsigned int const*, int, QPixelLayout const*, unsigned int const*)
which called from QWidgetBackingStore::sync().

viewport is seted ad follows:
Qt Code:
  1. QOpenGLWidget *widget = new QOpenGLWidget;
  2. QSurfaceFormat format;
  3. format.setSamples(4);
  4. widget->setFormat(format);
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Is there any ideas about the reason of hight cpu load with QOpenGLWidget?

Mac OS X 10.9.5
Qt 5.5.1 clang