Fat Princess is great fun, but also - at least at the moment - a pain to play over the PSN, courtesy of some choppy online performance.
Developers Titan Studios hear your pain, however, and promise a fix is on the way. The cause of the issue is the game's matchmaking, which is accidentally pairing players with abnormally high pings. Hence the poor performance.
"Rest assured," they say on the company blog, "we're working on it, and think we have it largely addressed." Hopefully so! Be a shame if this kind of thing stood in the way of people buying/playing one of the most enjoyable PSN games currently available.
Update from Titan: Fixes Coming [Titan]