psh everyone else posting cant or isn't able to run t6 and they troll cuz mad.
i run t6 (hardcore) with 18-20 second kills, and this is what i use.
in order to run t6 ghom with a barb, you have to have a very particular set of gear to do it effectively. you have to improvise with talents where certain gear falls short. i use this certain talent build for my barb. with different gear, you must use different talents to make up for losses in toughness, or damage to do effective efficient runs. you usually want ghom dying BEFORE or right when WoTB cooldown finishes.
Barbarian - Game Guide - Diablo III
As far as gear goes, try to get 2pc cains/aughilds/BT set with ring of grangeur/soj. I don't use magefists because i use cain glove/boot, BT leg/belt, aughilds wrists/shoulders, cindercoat, andariel helm, fire trifecta ammy; and sun keeper weapon and burning axe (or devastator) weapon for fire/ele dmg.
All talents being used are fire talents so you can tell im going for as much elemental/elite damage as humanly possible.