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QApplication::processEvents timing

  • Hi guys,
    We are using Qt for a visualization engine viewer, and we are having issues with the QApplication::processEvents() method.
    Since we needed to control the framerate (in a game loop fashion), we overrided the QApplication to define our own and our game loop that looks like

    MainApplication app;
    // Some code here
    while (true) {
        // sync code, nothing for now

    This works fine, timing are about 0.001s for the processEvents() call, while, for an empty scene, the doFrame() takes about 0.0001s.
    Now, we have a problem when we double click on title bar (to maximize the window). Indeed, after doing that, processEvents() call, goes from about 0.001s to about 0.01s (*10). Is this a known issue when using QtOpenGLWidget ? (most of the time seems to be taken in QPlatformBackingStore::composeAndFlush())