Ah? It should last around 2 hours, usually (like to what your 2.5 hours with interval comes down). I don't remember anyone complaining about the length when we went to see it in high-school; which speaks for itself, I guess, eh :-). The French performances (which are relevant since it was written in French) I can find last between 1h45 and 2h10. Perhaps in the US, like for TV programs, they inserted a total of 45 minutes of commercial breaks ;-)