Absent some unusual circumstance, I'd walk airside around the loop. I think my landside walks around the loop (before the B/C construction block) were 20-ish minutes. A <-> G landside would be no less than 10 minutes if the stars are aligned. And I've found the int'l security checkpoints to be amongst the least efficient - a couple weeks ago during the evening A didn't even have a dedicated Precheck lane - it did to enter the checkpoint, and then you got a card to show the agent inside, so Mr. and Mrs. Bumbles and the kids could easily be right in front of you for their annual trip to wherever.