It's clear that the biggest problem is companies prioritizing their cost, at the expense of user experience.

But after that, the biggest problem is clearly the framework/language you use. The maxim "premature optimization is the root of all evil" has done damage here. The problem with frameworks/languages is that by the time you finish your features and profile your code, you're already doomed. There's no way to speed up the entire framework/language, because it's part of everything you do - death by a thousand cuts. Nothing you do can improve upon the fundamental fact of running in an interpreter, with a garbage collector, with complex layout calculations (a la HTML/CSS instead of Win32), or with major choices like processes over threads, sync IO over async IO.