File size

I’m currently making a relatively small cartoon. I’ve got the preloader, and the first 10 or so seconds of it done. By the end, I think it’s gonna be aroung 3 or 4 minutes. Now the file size now is around 600kb, which seems absurd considering how short the movie is. What can I do to lower my file size? In the end, it has to be below 5 megs or sites such as newgrounds won’t allow me to post it. I don’t even have the sound file in yet!

Should I go through the movie and and optimize the shapes (all the characters will look like crap though). Also, does the amount of things in my library effect the filesize? All the tweens are there for some reason. I can post my fla if you need to see it. Any help would be appriciated.

Tom