I've taken a few long breaks so I don't remember if it's gotten better or worse but I think it's gotten worse because I lag anywhere even if I'm not killing anything, though curiously I don't lag at all in amoria pq, which might be worth looking at to see what's different in there as oppose to everywhere else.
It's not that the exp is bad, it's that mobs are giving too much exp. 1 pq will get you enough exp to almost level in your 50-100s last I checked (which was years but I don't see why nexon would change that). Questing, Party questing, Bosses should ideally be the best way to earn exp and it used to be that way. Leveling is way too fast now. What we need is a heavy reduction in everything especially the amount of exp that mobs gives so that it is faster to pq. Not saying we should return to the days of 2006 where it took a month just to get to level 60 but it should not be so easy that people can get to 200 in under a day.