"Not once have I ever seen somebody try to derail a process of "ascertain speed is an issue that should be tackled" -> "profile" -> fix the hot path."
That's because your boss will never in a 1000 years hire the type of dev who can do that. And even if you did, there will be team members who will fight those fixes tooth and nail. And yes, I have a very cynical view of some devs but they earned that through some of the pettiest behavior I have ever seen.
Man, what are you talking about? Speed optimizations after shipping software happens constantly in everything from video games in C to ui libraries in js and everything in between.
People write some code, test it, ship it, then get some ideas that its too slow and make it faster.
The nice thing about doing it with shipped code is you can actually measure where time is spent insyead of guessing.