it's gonna sound silly, but it works, especially if u have an af assist beam (panny users). The speed part is kinda bogus since your gonna waste time dialing but, in really dim light the PEN and panny might not even achieve focus (happens to me all the time even with assist beam), and this way they always do.
First you have to shoot in A mode, and set aperture and ISO (no auto ISO), then dial your EV compensation all the way to the + side (+3 EV), whats gonna happen here is that the shutter speed is gonna go way down but auto gain is gonna make the lcd very bright (much brighter than it was at least). At this point half press the shutter for autofocus, you're gonna find that were it didn't focus at 0 EV it now easily focuses! Once you've focused dial back the EV without letting go of the shutter and then shoot. It's much faster in practice than it sounds like and it's definitely much faster than misfocusing 3 times (and having the people look at the beam 3 times) or manually focusing in a dim LCD.

That's a nice and useful glitch!