100% cpu usage

iv been working on a game since springbreak, and have started having serious cpu issues, would any of these be a reason for a max cpu usage?

*lots of movieclips, about 20-30 mc’s during a fight, but game lags even when no shooting is happening

*large mask, i put a masked layer in my game, to give the appearence of shadows, can a gradiented moving mask be a big problem?

*removemovieclip/unloadmovieclip, to make sure my mc’s go away, i put both just to be sure

  • most of the coding isnt on the main timeline

*reaching borders of flash when making game

if any of these looks like something that can make a game lagout plz let me know

thanks in advanced, nick pearce