Most. annoying. thing. ever. I have not been able to get this to stop. I "feel" that it slowed down when I set the refresh interval in the app to the highest value (15 mins) but that could just be my imagination.
I recommend one of the Facebook app alternatives. I've used Facebook Touch before and found that kind of nice (hated the icon for some reason). Maybe someone will pop in this thread with a better alternative app (or a solution for the real app)