Comment 6 for bug 981210

I found this

http://stackoverflow.com/questions/10307860/what-is-difference-between-qimage-and-qpixmap

The behaviour described in the last comment is exactly what I can reproduce.

For an Image that is just painted once, QImage is faster and QPixmap is faster when I want to draw something fast more then once. I've adjusted your test project a bit to also show the time for the first rendering and to throw away the first 100 measurements for the mean (the mean is now visibly more stable instead of decaying over time)

Qt 4.8 Debian Wheezy
QPixmap: min 56 mus , mean 116 mus, first render 31804 mus
QImage: min 54 mus, mean 120 mus, first render 26442 mus

But I doubt how valid this test is since I get the same results if I render both times a QImage/QPixmap