> I suspect a lot of games leave a fair amount on the table.
I worked as a programmer for a AAA game. My feeling is that there needs to be someone in the team with enough influence who cares about optimisation enough to invest a lot of time on it.
After working on the game for a while I had enough political budget to spend time fixing ocasional frame stalls that annoyed me, which felt nice. I also worked a bit on general optimisation, but mostly on stalls. There were definitely lots of people who cared about performance, but this probably varies from studio to studio. If I hadn't done this, I'm sure someone else would have fixed some of them, but not necessarily all of them.
Let's also remember that lots of teams are under tight pressure and deadlines to deliver features and they may not have time to work on performance even if they want to - and if you're using an external engine, this gets even harder to work on.
Anyway, just my 2 cents, maybe other people who were in similar contexts will chime in with their own experiences.