Major performance regression in Qt 4.8.0 OpenGL

I have an app that is using QtOpenGL. I was first running it on Qt 4.7.4 and then on Qt 4.8.0 RC1 and it was running fine, but when I switched to the final 4.8.0 release I noticed a major performance regression. I normally get around 400 fps on average in my application, but after upgrading I only seem to get about 65 fps.

It is not a hard lock as it will randomly drop much lower under load, so it is that every frame is taking much longer for some reason.

I have put together a small sample application that I have attached that also displays this issue. When building and running it with Qt 4.7.x or 4.8.0 RC1 dlls it runs at really high framerates, but when run with Qt 4.8 final dlls it drops to about 65 fps.

I get the same behaviour both when running release and debug builds of the test application.

I got my Qt 4.8.0 from the installer for Visual Studio 2008 on the Qt Webpage.