Yes, they do. OGs remember that Facebook circa 2012 had navigation take like 5-10 seconds.
Ben Horowitz recalled asking Zuck what his engineer onboarding process was when the latter complained to him about how it took them very long to make changes to code. He basically didn't have any.
If it's true that nobody is getting promoted for improving web app performance, that seems like an opportunity. Build an org that rewards web app performance gains, and (in theory) enjoy more users and more money.
Ben Horowitz recalled asking Zuck what his engineer onboarding process was when the latter complained to him about how it took them very long to make changes to code. He basically didn't have any.