well its easy to miss there, so deceptively named as "Speed Run", easy to confuse it with something else
it can be a right bitch to get as well, I've still not managed it. You have to know the level BLOODY well and be able to do it without mistakes because you only get about 3-5 seconds of slack on the level
It's mostly because I only ever glanced at the achievement list and didn't scroll all the way down on my Xbox. most the ones I saw were just "complete this, traverse that."