return to castle wolfenstein and quake 3 runs flawlessly 100% framerate as been said, it seems it's just doom 3 that sees some performance dips. It's more playable than your tab monstercameron but not quite as good as quake 3 or something.
I'm still messing around with the settings but when I try to change the ingame quality it crashes the game out and I have to delete the config files and try agian. If I turn off tegra enhancements it takes forever for the game to load and I just exit out. So I'm still playing with options.
I also can't figure out how to use the analog triggers for shooting, I can only use the shoulder buttons. The analog sticks work great in all of them for movement, viewing and mouse navigation.