I don't think I've cut anything yet that has made the rpm's drop. I've tried to get the rpm's to drop by blowing all of the cut grass into the uncut area in really tall grass. Even then it doesn't phase it. I'm sure if I went through it at 12mph I would hear the rpm's drop. I just put 100 hours on it yesterday. I don't have any hard consumption numbers for fuel, however I'm using Ethos in it and if I had to guess I would say it's around 1.75 to 2 gph.