Trying to hide indivdiual tiles in tilemap effectively

Hello to Kirupa!
I’ve been working on a game for the past couple of months and have gotten to the point where it’s almost ready - however, there is one part that has me completely stumped. My tilemap rendering class works the way it should, loading a file from XML… however from there, to make it more efficient I’m trying to figure out ways to hide it when the map goes off-screen - past particular x/y coordinates. So far… I’ve studied Tonypa’s AS2, but can’t figure out how to apply it to this:

http://pastebin.com/x2x9mn6j

Each tile is a movieclip object with different frames to switch to depending on conditions based in the loaded XML file.

Can anyone suggest anything?

Edit: If needed a rewrite is feasible, but the tile assignments need to be kept.