Beating the French Defence in 18 moves

Although my opponent is rated ~150 higher I wasn't convinced by this line in the French. I don't see the point in 3...c6, I think it just wastes time. I'd normally play the immediate c5. The only serious mistake I think black made was 16...Nxg3, allowing 17 Rxg3 and an unstoppable kingside attack for white. OK black has a cramped position but white has no real threat until Nxg3