@Zukow x5000/020 with 2ghz : 17 fps. Probably x5000/040 with 2.2ghz will be around 20, and so G5 with 2.3 22. Seems all sane enough everywhere then. SDL1 version used in your tests?
EDIT: managed to get 18 fps on my x5k/020 with removing from memory all crap i have loaded on running. That with SDL2 version.
