Spin ups.
Common mistake people make when matching an acceleration is to assume you need to increase torque. You don't need to go to a 53x12. Quite the opposite. That would be like trying to accelerate onto the freeway from 20mph by shifting your civic into 5th gear. No acceleration. Try shifting down. High cadence might cause your torque to be less (which is better for repeats) but since POWER is a function of cadence and torque you will find that you accelerate better and faster, plus you will be able to repeat.
I hate to say practice practice practice, but it is the truth. Stop mashing the big gears. I would recommend form sprints, spin ups, and/or fixie work with a very light gear for you. Stay out of the big ring at all costs in training for it, and try shifting to a BIGGER cog when you want to accelerate.
Huge difference.