I know giants that run it in 10 minutes on average. 6-8 with trans. It's possible. They did it under level 3k too.
Yeah... GFS just destroys that mission. Also helps in the boss room when you can't use adniel. I had a case where I did manage to do 3 runs in a day and ended up using a r3 fireball crystal with tower cylinder to get most of the mobs. x3