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X11 vs XP graphics performance on QT 5.2.1

  • I have a simple app that has three QLabels layered with 1 on the bottom, 2 on top of 1 and 3 on top of 2 and 1.
    In the first Qlabel I load a JPG image. In the second I load a PNG image that has an alpha channel.
    In the third Qlabel I am showing an incrementing number. I used a timerEvent the runs every 30 msec that increments a number converts it to a string and put the string in to the label

    void ImageTextTest::timerEvent(QTimerEvent *event)

    I have built my app in Windows and on Linux and then run it on my test unit.
    On the test unit I can boot either XP or Linux (lubuntu).

    If I run my app on XP and look in taskmanager it appears to take almost no cpu load.
    If I run my app on Linux and use Top it seems to take about 21 to 23 % on one core for the app plus another 7 to 8% for Xorg.

    I have tried using -graphicssystem (openvg, opengl, raster) on the Linux box but did not see any performance difference.

    So my questions.

    1. Is lower QT graphic performance typical on Linux vs XP?
    2. How do I tell which graphicssystem the QT app is using?
    3. Is there some test I can run to see which graphics systems are supported on a PC?


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