Ascertain an issue is too late for bad software. The technical term is polishing a turd.
Not that what you're describing doesn't happen, people trying to make something irrelevant fast, but that's not the big problem we face as an industry. The problem is bad software.
There's too little appreciation today for a well designed system. And the "premature optimization" line is often used to justify not thinking about things because, hey, that's premature. Just throw something together.
Many things need to be optimized before you can easily profile them, so at this stage its already too late and your software will forever be slow.
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.
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.