Yeah - you're right about the lag spikes on web version. Are you using object pooling for the bullets?
Also does the hit box change on orientation of tank? If so, that's an interesting quirk.
Anyways, forget the tech, this was great fun. Have to hand it to you, the last boss was tough. Made a few moves that made me face palm. This game has a certain... i dunno, can't put a finger on it, a je ne sais quoi if you will...
Loved it. Great job!