I understand the performance variance characteristics, what concerns me about these tests is that the graphs of them are not continuous, they seem to be immediate dips instead of gradual curves. This indicates to me that the sample size wasn't large enough, or at least the graph needs a higher resolution if data exists to support it. Also, at the bottom, the article gives the numerical data, with the mean and standard deviation. However, the mean for the hosts with high standard deviations are essentially useless, because the standard deviation is so high. If we are going to compare average performance between cloud hosts, lets at least have useful averages to base our opinion on.