> I always ask them to either prove it or write the simple thing. Even if they do, they also need to make a case that in this specific case, performance matter

> I always ask them to either prove it or write the simple thing. Even if they do, they also need to make a case that in this specific case, performance matters enough to pessimize code simplicity and maintainability. Also, if performance is that critical, it's imperative to benchmark again after each compiler release to guard against codegen regressions. And benchmark after changing this piece of code. Otherwise, we can say that performance doesn't really matter.