Isn’t not that they’re “not perfectly accurate”, it’s that you can find half an order of magnitude of performance after the profiler tells you everything is fine.

That’s perfectly inaccurate.

Most of the people who seem to know how to actually tune code are in gaming, and in engine design in particular. And the fact that they don’t spend all day every day telling us how silly the rest of us are is either a testament to politeness or a shame. I can’t decide which.