I’m with both of you and I don’t think what you two are saying is mutually exclusive. I’m kind of a performance nut (often working with teams, I’m the guy that introduces everyone to a profiler) and, in my N=small experience, PMs are opposed to spending time on performance optimization precisely because most people are bad at it and it takes an undefined amount of time for unknown performance gains.
When I take an hour to profile and analyze some request and say “I think we can cut this thing’s response time by 80% by optimizing $X, which will result in an overall page load time reduction of 3s”, that’s way easier to sell than “I want to figure out why this page load is so slow” and then reporting back a week later with “shrug I optimized 5 things and it didn’t get faster. Dunno.”
When I take an hour to profile and analyze some request and say “I think we can cut this thing’s response time by 80% by optimizing $X, which will result in an overall page load time reduction of 3s”, that’s way easier to sell than “I want to figure out why this page load is so slow” and then reporting back a week later with “shrug I optimized 5 things and it didn’t get faster. Dunno.”