It climbs to a level and then will drop down when the garbage handler gets rid of the garbage left behind. nUI just has a lot more to deal with. Scott is, I believe trying to cut down on how much there is with nUI 6.
I personally don't even notice it myself but I have titan and when I do spot it I do a manual garbage collection but I've let it go on for hours and watch it garbage collect itself. Not as often as I like but its dealable with
