I think that most df speedruns... Are not in fact speedruns. Most take as long if not longer than doing it normally. Constantly I see tanks doing giant pulls back to back, never stopping for melee to get TP and then the melee sit around doing nothing until they get enough TP back to actually aoe, making those pulls take forever to kill and draining the healers mana. Which you then DO have to wait for. If you have a good BLM and WHM who can really pump out the aoe nonstop then great. But if that isn't the case it more often than not makes the run take longer.