from level 33 to level 40 it took me like 2.5 hours...

the way i did it:
i pressed on the door for about 50 or 80 times....
then i used the teleport to reach the northwest room with 2 statues
then i went out from the room to the north of the map
in there there was a LOT of mobs and i mean LOT...
my game almost crashes...
to kill them i used whrilwind blindly
with life leech so i didnt die...

each round of that i got around 70k-80k xp
and at lvl 40 it was around 15k-20k xp

because of that i reached to Hall of Echos at lvl 42...