Thanks for your input so far. You are right, the thread lock could have been the problem, but I think it is not. I read the data from shared memory in a separate thread now and the problem still exists. I did some more testing and it seems that the problem is neither related to shared memory nor to the procedural mesh update. The lag even appears in a very simple scene with just a few spheres and cones (but it is a lot less than compared to my 3d reconstruction scene). Maybe it is some driver issue, I dont know… The hardware should not be a problem at all.