Just wanted to add that I did bad in describing the effect I have. What I mean is not the typical notion of tearing related to V-sync issues. What I mean is that small decoding blocks tear from the keyframe on for 1-2 seconds. So if there is a zooming or pan in the scene, you can see how they smear along because more and more blocks do not get updated properly. I don't know how to better describe this but will try a screen capture soon.