That is very unusual, I haven't heard of variance of that degree before. In your main DirectRT window, do you have an UPDATE option? If so, can you click to update your beta to the most recent version and see if the image priming sample gives you a similar pattern of data? I'll pass this on to Trevor our lead programmer who might have additional suggestions. Attaching a dxdiag.txt file could also help so we can see the details of your hardware (e.g., to figure out why v2006 could perform better on this machine).