This seems to be popping up quite regular with the play and loop object commands. Apparently you get a better frame rate if you just set the current frame yourself without using the built in play and loop stuff.
EDIT: What 'revenant chaos' said really...
After reading through some of the history on the forums relating to this. DBPro seems to calculate each frame from the beginning on each frame which isn't really necessary. So something to do with key frames or absolute frames does make the difference.
Mental arithmetic? Me? (That's for computers) I can't subtract a fart from a plate of beans!
Warning! May contain Nuts!