Finish any level in under 10 secondsThis won't be possible until you complete the level 'Run!' early on in Chapter 1. During this level, you'll unlock the ability to hold to make your character(s) run, which also allows them to skip over certain interaction points. Complete the level 'Run!' like normal, then replay it and just hold so your molecat runs past the chute and right to the door (just make sure to let go of before the door so you don't run past it) and quickly press to end the level. This should allow you to finish the level in 5-6 seconds.
NOTE that using is not possible for this achievement, as it only speeds up time (time still accumulates like normal), so don't bother using during this achievement attempt at all.