I've always been painfully slow off the floor when I deadlift. I made a concerted effort to prioritize my front squats recently (and upping my squatting volume in general) and was finally able to conquer 600 pounds. The additional squatting helped improve my quad strength and ability to push away from the floor when I initiated my pull.

Heed my warning, though. If your deadlift volume is up it'll behoove you to opt for more front squats or high-bar back squats since both will allow you to maintain a more upright torso (less shearing on spine). If deadlift volume is lower, feel free to implement more low-bar back squatting.

Long story short: Don't neglect your squats.

Related:  30 Days of Deadlifts

Related:  Advanced Tactics for Advanced Deadlifters