Not having direct access to the data, I still find it difficult to offer a good explanation, but certainly Ninga's_RGR'us suggestion that the Duration timing is inaccurate may account for much of the discrepancy. If I was faced with this issue, I would probably not worry about it, as the goal is to maximize overall performance, and not worry about some arbitrary statistics. If you are happy with the current performance, then the stats you see aren't important. If you are not happy with the current performance, then I would start experimenting with alternatives to see what I could do to boost performance in order to reduce the overall time it takes to accomplish your task. While tools, such as Profiler, can be handy, they can sometimes also lead us astray, and distract us for our ultimate goal.