framerate dropped from 900 to 50 when switching from 5.0.2 to 5.1

Hi,
My application (3D viewer) is using a QTimer with a delay of 1ms, which trigger an update, which cause window to be repainted (and the 3D scene to be rendered).

I used to have a timer of 0ms, but I have came accross some big issue: application freezing, docked widget not responding anymore when moved, etc...
The only way of solving the issue, was to:

• set the timer as a single shot with 1ms delay
• at the end of the "paintEvent(QPaintEvent *event)" method (i.e. the method that indirectly gets called when the timer event is triggered), manually start the timer again with a 1ms delay (single shot)

I think this is related to the issue as well: https://bugreports.qt-project.org/browse/QTBUG-29435 - this all comes down to the event dispatcher on windows I think (although my experience with Qt internals is quite limited).

Now, back to this issue: I switched to Qt 5.1.0, since that my framerate dropped to 50/60 FPS (instead of 900 FPS for an empty scene), i.e. the timer resolution seems to have dropped to 15/20 ms instead of 1ms.

I am using Windows 7, and noticed the following change in "qeventdispatcher_win.cpp":

if (QSysInfo::WindowsVersion >= QSysInfo::WV_WINDOWS8) { // QTBUG-27266, Disable when running MSVC2012-built code on pre-Windows 8

So basically, there is no way to use a high-precision timer in Qt anymore ?
I think there is a real problem in the event dispatcher, this issue simply being a side effect. Getting rid of the high precision timer is a hack rather than a real solution (with many side effect as the frame rate drop I am experiencing here) - switching back to 5.0.2...