Some poor running games are probably linked to
"high-end" computers of the developers.

It is hard to see framerate issues, if you develop on a machine
that is on the top-end of the targetgroup.
(the game is developed for the customers, not the pleasure of the developers)
The developers should at least have a low level machine permanently ready for
testing.
At least the person who assebles the game-content
(lead programmer) should work (have available)on a mid-range machine.