Simple functions gets close to the baseline in run time and because of that will be very noisy. When calculating a mean we actually do a low-pass filtering, removing high frequency noise. Still there will be noise and the only way to avoid it is to make longer runs (larger sets and more sets). Take note of the maximum and minimum run time, if they are to far from each other, or the standard deviation gets large, then it is very likely that the load situation on the server makes it difficult to get good results.