We arrived at 1pm Saturday expecting it to be impossibly hot and crowded, but happily it was only impossibly hot. The festival was well-laid out over a couple of blocks of somewhat breezy waterfront in Jack London Square, and well-managed. We didn't wait more than five minutes on any lines for food, (though we had prepared for trouble and fed ourselves banh mi before hitting the fest), and the very most popular places looked as if they had a 20 minute wait. There were some nice surprise foods--the "sexy soup" lady who pedaled up on a tricycle offering a chilled tomato-ginger-miso soup rich in umami refreshment, the vegan cupcake people with $1.50 bitesize chocolates and bigger vanillas, I don't remember what else. It was good to take a break in the indoor section, where I guess the JLS indoor market is going to be, though nothing inside was new to our party who are regulars at local farmers markets.
Some new-to-me and good foods (sorry I don't have any vendor names, I wasn't carrying a bag and it was too hot to do much thinking)--
the roasted nuts ($2 for a cone);
the roasted piementos de padron;
really excellent farinata;
watermelon paletas from a South San Francisco company (which had no line, right next to the honeydew-wasabi and other whoop-dee-doo flavored paletas from the company in Santa Cruz, which I have no doubt were great but were twice the price and had thirty people queued up).
Perhaps because of the heat, the traffic flow was fine. Shady spots were coveted but people were mellow.