All the telling similes I can briefly think of, from "in Chad drinking water availability does not reach 40% and in Namibia exceeds 80% - but see what it feels like, and how comfortable you are with that" or "near that peaks the temperature is 10°C, and in the valley 20°C - but see what it feels like, and how comfortable you are with that", seem to be part a much more sophisticated reality (the "ceteris paribus" constraint is less foreseeable) than that of "on that machine this defined code runs in half the time of that one" - especially when you are trying to get an idea of the world, not to see how you will feel like and how comfortable you are with that.
You can decide beforehand if increased speed with respect to your experience on your machines is beneficial to you or not.