Im telling this as a War, but im pretty sure it works almost the same...

First rule is the one already told in this thread... If you don't have 2 big aoe dps ( brd and blm ) don't speed run. Then if you have any other job, Pull 2 or 3 groups and MARK enemies, is something ppl forget just because they are speed running, and that's incorrect. Mark so if you have a mnk or a drg you are going to know which enemy is going to go down first

After that just spam things.., remember to spam many of your ogcd as you are going to take less dmg and healer hate it's going to grow at slower pace.

Another question, do you move while tanking groups? This is completely necessary to avoid aoes and to reach everything with flashes.