Definitely currently a lag in some of the mini-games, until it can be fixed, I'd say up the time a bit in them to make up for the 3 seconds you lose per lag (and sometimes there are multiple lags/freezes in 1 30 second game.) The matching in the MRI game also seems to be a bit off right now, sometimes you have to click the same square twice, because by the time you click the match, the original square you clicked has disappeared. Absent of those two bugs, it would be a lot more fun to play that specific game.
I've noticed I've been getting a bit of a lag the more I played this game; the higher level I am, the more character sprites there are in the building. Maybe the processing is getting a bit slow? I don't know, has the game been lagging because there are too many patients to treat?
I'm having the same issue myself! I have 2 Facebook accounts and one is strictly to play games on and the other one is just for personal use. I have House MD for both accounts though my gaming account has over 25 friends I added on there and I'm experiencing tons of lagging throughout the game and it's affecting my performance on there. The other one I only have 3 friends on my game and I'm not having any lagging on that account at all so I definitely believe that it has alot to do with the amount of people you add. Either way the lagging is a problem and hopefully it will get fixed.