Seems to be one hell of an acoustic environment. (or perhaps they had direct feeds and it was professionally mixed, possibly with canned cheering)
But no. Best performance by a lead singer I've seen was by Lacey Mosley of Flyleaf. A little firecracker totally singing her heart out.
Best musical performance was by Sheryl Crow. She was touring with John Mayer, but Mayer had to pull out of the performance I had tickets to due to a sudden onset of laryngitis. (Quite the serendipitous occurrence, as I didn't want to see him anyway.) Most people turned back at the gate, but boy did they miss out. Sheryl put on a marathon performance. No warm-up acts, no intermission, just hours of her singing.
She's one of the few pop artists with the discography to pull it off.