Miley Cyrus in White Pants Performing @ Z100’s Zootopia 2008

On Saturday night, for approximately two and a half hours in the middle of Zootopia 2008, several thousand young girls were held hostage at the Izod Center here. They had come to scream for the Jonas Brothers, the preppy New Jersey sibling heartthrobs who opened the show, and for Miley Cyrus, the teen queen who closed it. That there were eight acts in between was a sort of cruel punishment.

Slickly choreographed and arranged, Zootopia thrilled in inverse proportion to the age of its performers — beginning loudly with the Jonas Brothers (average age: 18), dulling in the middle with a reunited New Kids on the Block (average age: 38) and finishing, amid a sea of shrieks, with Ms. Cyrus (age: 15).

Conveniently, the youngest performers were also the ablest. The Jonas Brothers, who play instruments and sing as a full-service boy band, veered from loose-limbed rock (“Hold On”) to intense balladry (“When You Look Me in the Eyes”). They were a model of precision.

Ms. Cyrus, whose popularity appeared undiminished by recent scandal, was slightly less focused, though her flashes of fatigue did little to diminish her blunt-force hits — “See You Again,” “G.N.O. (Girl’s Night Out)” — or their reception. She performed songs from her forthcoming album, “Breakout,” that indicated she’s not meddling with success, although “Fly on the Wall” curiously echoed the B-52’s “Rock Lobster.”

Miley Cyrus in white pants performing @ Z100’s Zootopia 2008 in New Jersey