Comment by LegionMammal978

"Multiple times" doesn't have to mean "no modifications". Suppose the software is currently on version A. You think that changing it to a version B might make it more performant, so you implement and profile it. You find no difference, so you figure that your B implementation isn't good enough, and write a slight variation B', perhaps moving around some loops or function calls. If that makes no difference, you keep writing variations B'', B''', B'''', etc., until one of them finally comes out faster than version A. You finally declare that version B (when properly implemented) is better than version A, when you've really just tried a lot more samples.