This was Gelly's idea, so if you want a better understanding of how it works please see his video concept:    • limbo: drewbox pause buffer potential  
But basically, the menu starts scrolling fast because I'm holding inputs (up and right) that will take effect as soon as I unpause.
It's not easy and still feels unreliable. If you need to correct the first pause at all like in my last example you'll be losing quite a bit of time.

Estimates:
normal strat = +0.0
second box launch (previous video) = -1.6
first box launch w/ fast pause buffer = -2.0
first box launch without pause = -3.2