heroics take like 20 minutes for multiboxers
Man, not for me. Gundrak is my farming fav (only due to 5 badges and familiarity) and I'm still 45 mins on a fast run there.

I do UK with no problem as well, but its a grind of trash for three bosses.

I probably need to expand my horizons on farming instances. To be honest, by the time I started clearing them I blew through badge gear (pre 3.1/2) so fast that I stopped farming them. (Had nothing left to upgrade.)