If you mean "doesn't stutter" when the screen rotates or you switch tasks, I'm with you. I really like Someplayer, but the stuttering is too annoying. I guess it has something to do with not using the MAFW back-end that the standard player uses.

So I've been using the open-source version of the stock player in order to get a working portrait mode.Much easier to operate in portrait at the gym and in the car.

That one does not stutter because it uses MAFW just as the stock player does. It isn't quite feature-complete yet (e.g. no category view for videos yet), and there is no deb yet so installation is "for geeks only" but works great as far as the actual playing of music.