The new Broadway musical 'American Idiot' starts off at a fever pitch -- and stays there. By the time it ends, 90 minutes later, you may feel more numbed than stirred. Based on Green Day's 2004 concept album of the same name, the show, which opened last night, delivers an impressive amount of terrific numbers. Many have a genuine melodic pull underneath their brash power, and they are imaginatively, punchily staged by director Michael Mayer ('Spring Awakening') and choreographer Steven Hoggett ('Black Watch'). If only we could take a breather once in a while.