Pretty amazing, but
I don't think you have added in the removeMovieClip() function, or whatever is needed, to remove flames, bullets, rockets etc. after they've spawned.
Mine ran fine for the first 30 levels or so, but started to lag up.
It was very fun, however, and I loved the thrill of having to create a suitable path whilst spamming ground to stop those damned grenade launchers XD