Skrillex is slight, but he is not small. His hair is long and stringy and flies around his wet head like a damp rag. And he wears a motion-capture suit during his performance, giving life to a robot doppelgänger displayed on a huge screen that mirrors him as he pokes at his laptop and the rest of his gear, and as he puffs a cigarette quickly between maneuvers and pumps his fist in the air, prompting the several hundred moist teenagers in the room to take a break from bounding around like electrons and raise their fists right back at him.