The fastest run of the Loop Trail we have found is Sean Meissner's 3/29/2014 as posted here: http://www.marathonmaniacsdb.com/Maniacs/MyRaces/92
Meissner said: "New fkt (despite getting lost quite a bit)! Great run around Flag."
I believe I was the second person to run this full loop when I ran it almost 10 years ago (Scott Bajer being the first). I ran unsupported, carrying all of my food and gear for the whole run, and refilling water twice at fountains/spigots along the way. As I ran this before the loop was fully signed, I figure I spent about 45-60 minutes getting lost, backtracking, and consulting my map, and I'm confident I ran the correct loop. I started/finished on the north side of the loop near the Pipeline Trail.
I always thought a super cool double would be to run it, then immediately bike it. That would be a big, fun, normal Flag day.