I do not believe orbs have an infinite lifespan, just a long one. At this point I am going to have to retire from the server, atleast going out and doing things beyond my fort walls, until 1.9 because of this. I just had a death about 15 minutes ago, and standing on the exp splat for 13 minutes I'm still at 2seconds per frame. Yes, that's how much exp I've acquired over the weeks, especially since I ended up accidentally cleaning up a few other players' exp puddles too, so I am the ticking time bomb. Already made the server crash from the sudden appearance of the fountain.