You couldn't know, but my job is 50% about optimizing computational workloads. But many times, when questionning my users, it happens that they want an optimisa

You couldn't know, but my job is 50% about optimizing computational workloads. But many times, when questionning my users, it happens that they want an optimisation for some code that will run 2 or 3 times. So eventhough they'll have to wait a week for the computation to run, it'll take me just as much time to make the optimisation run :-) But if code happens to be used 10 times a week and takes about a day or two to run, it's a no brainer: spending a month optimizing for 10% speed increase is worth it !