Ddzc: The only problem with spraying is that you have to spend so much time masking off everything you don't want to get sprayed. But, if you don't mind getting stuff all over everything cuz it's gonna be covered up later anyhow, that's probably the fastest way.
However, be aware that you can't really spray bare drywall or bare joint compound without back rolling. A spray gun just doesn't have the pressure to drive the paint into the porous surface of the drywall or joint compound the way a brush or roller does, and so you don't get very good adhesion of the primer to unpainted surfaces without a follow up back rolling.
You might want to talk to the people in the paint stores that sell paint sprayers. They'd know more than I.
What I do is paint all my corners with a roller that has nap on it's end as well, so that the paint gets right into the corner. Then I allow that paint to dry. Then I use a piece of sheet metal with some painter's masking tape on it's edge (to prevent marking the wall) and use an ordinary 3 inch paint roller with the sheet metal to paint right up to the corner (but not get any paint on the opposites side of the corner). Then, I fill in all the walls where the edging has already been done using the two previous rollers with 10 inch rollers.
That's about the fastest way I know of to paint without using a sprayer.