It can be easy to feel beaten-down and bedraggled on the third day of a three-day festival, especially if you’re not a teenager anymore. And the third day of this year’s Pitchfork Festival started like that, with the great Waxahatchee playing a warm, pretty set that never quite achieved liftoff. (It wasn’t their fault. It’s just hard to stand in the sun for a third day straight and listen to gooey, introspective music.) But the final day of the festival turned out to be the most cannily booked. There was no fat on the bill, and no heritage acts bogged down the main-stage lineup. Instead, we got a fascinating and all-over-the-map succession of forward-thinking artists, people with things to say and interesting ways to say them. And energy. In the end, the day built to the performance of a lifetime from a hometown kid who knew how to seize his time.