One of the reasons I love Go is that it makes it very easy to collect profiles and locate hot spots.

The part that seems weird to me is that these articles are presented as if it's a tool that all developers should have in their tool belt, but in 10 years of professional development I have never been in a situation where that kind of optimization would be applicable. Most optimizations I've done come down to: I wrote it quickly and 'lazy' the first time, but it turned out to be a hot spot, so now I need to put in the time to write it better. And most of the remaining cases are solved by avoiding doing work more than once. I can't recall a single time when a micro-optimization would have helped, except in college when I was working with microcontrollers.