I've got the same problem--only moreso.
Choppy, yes. Like a pig, yes.
Granted, I'm the first to admit that there's more than likely a lot of user error here and am going to try some of the mods listed above.
I'm running on a 1.5 machine (athlon 2200+) with 512mb ram and it's very, very choppy. The set-up seems pretty sluggish and the form elements don't seem to retain information--maybe that's normal, but it makes me quite miserable when I re-enter setup and I cannot see the settings that I previously made, so that's a huge usability issue to me.
I like the look and feel of WinMC a lot; it's easy enough to get around in, but I keep finding oddball errors about 20+ exceptions being met when I try to exit a game or even when trying to get out of the screensaver thing.
And, again--this isn't to ride on gameex; I'm sure there's not a lot I've done to help the cause in making it right since I was tinkering around 2a last night, but I'm willing to get some more advice!