I've been making my Flash cartoons for FredtheMonkey.com both longer and more detailed. Well with the latest of the bunch it seems like towards the end it begins to lag and not sync correctly. What the heck am I doing wrong?

I see lots of Flash movies that are very very long in length but don't seem to lag.
Any tips? I tried seaching for something like this on the board seach but it kept freezing up and timing out.