speed req? idk. my mnk does good dmg. I can do like 1k with a double stacked howling fist. it's my enmity that's the issue sometimes (though not normally). The issue I think is getting one shotted by the floor. scrambling for a safe spot only to miss it by like 1/4" and getting one shotted by the ground is the stupidest ***ever.
Have you tried running through him to where the tank is, I think that spot is always safe isnt it? Hate can be a bit wonky since he has a high defence or something that keeps damage down, so if your tank can't do enough damage it will be hard for them to hold hate against a job geared specificly for it.
A speed run is less then 8 minutes for ifrit I think but not 100% sure, I just know I've done at least one. I think it boosts the drop rates a bit but not 100% on that either, I just know in the dungions a speed run nets you an extra chest.