the NVIDIA GeForce 210 is simply too slow. The DWM service calls some DWM functions to validate which windows are shown (dwmredir.dll!CWindowContext::GetWindowVisibleRegion). And the DPCs also come from the nVIDIA driver: Total = 100191 for module nvlddmkm.sysElapsed Time, > 256 usecs AND <= 512 usecs, 61, or 0.06%Elapsed Time, > 512 usecs AND <= 1024 usecs, 19, or 0.02%Total, 100191try a better/faster card