A little while ago, I wrote a simple .NET application that performs X amount of requests and calculates an average speed of those requests. It does this by dropping the highest and lowest request times, then taking an average speed on the remaining requests.
This does a decent job for a straight up speed test. However, a few possibilities could arise, such as CPU hogging that could skew the results. Instead, I've made a few alterations and converted the speed tester to not be based on the number of requests, but instead based on a specific amount of time. This should help eliminate some inconsistencies of doing a straight number of requests.