I have seen very little code that is written to be "as fast as possible" and a lot of code that aims to be "fast enough" and fails to meet that bar. Perhaps still worth being mindful about it?
Show me a slow site and most of the time it's still the server holding it back on old hardware.
I was with you but mostly it really isn't hardware.
Mostly it's missing database indexes, n queries instead of a join, and sometimes just one small piece of code that's doing something very inefficiently on every request.