Can't do Grace in less than 10 Minutes :/

Any tips on this? My best time is 9:58 (technically under 10, I know) at the Rx weight of 135 pounds.

I'm 6' and 185 pounds. I can Power Clean 185 and can Squat Jerk 165, so I feel like I should be able to do this fast.

When I'm about 10 reps in my Quads (yes, quads) start really feeling fatigued, and my Jerk gets really week around 15 reps. Any thoughts? Do these areas of fatigue make sense or not?