In what context?

You are assuming the poster is doing something like your typical IO-bound backend, and not, say, a High Performance Computing simulation on a compute cluster.

I have done this kind of optimization to go from 24 hour compute time to 6 hour compute time instead for instance -- per simulation run.

How can you say "a few milliseconds" when you know absolutely nothing about the context?

I do not consider your advice any better at all; you assume all computer code is in the same context -- it really is not. Not all code is written as backend to websites.

You could have said "keep in mind that if you service is IO-bound, these kinds of optimizations are likely a waste" or similar to make the context clear.