You've all seen the Fleeting Shrines, right? They make you run quite faster. I have 24% base move speed and these add another 25%.
When you do your runs for your keys, do it in areas above ground or close to places where shrines have a high probability of spawning close to a waypoint. An example of this is the area in Act 1 right before the place where the Shinbone drops, there is an area that normally has at least 1-2 champ packs and almost always a shrine of some type. Why not start off your farming there towards your stacks and if a Fleeting Shrine happens to be there, then you are in luck. If not, at least you got some NV stacks.
Do not use it yet, however. Just note the location. Now, as you search for a fleeting shrine, obviously start killing towards your 5 stacks. After you complete your 5 stacks, go back to the shrine, use it, then enjoy a huge speed boost while quickly running and clearing easily over half to 3/4 of a zone before the timer runs out.
Hopes this helps someone. Can save a small bit of time.