>That's odd, because in my experience almost all games run best in "Borderless windowed" mode.

I think the difference is between when you tell the game to run that way in it's settings, versus abruptly forcing it by doing alt-tab. Games where their default 'full screen' is really 'borderless windowed' don't have problems when you alt-tab, but a lot of them act weird when their 'full screen' actually is a true full screen mode and you force them out of it by alt-tabbing.