Loaded .swf slowing down master .swf?

i created an animation for my homepage and it has a marked affect on the performance of the rest of the site. My site is a master .swf containing a nav and the layout. Each section such as home, news, audioplayer, etc. is it’s own .swf which is loaded and unloaded into the main .swf. why would a loaded .swf affect the performance when it has been loaded and not while it is loading. this is best illustrated by the nav becoming ‘sticky’?
how can i defeat this problem?

it can be viewed at the following url: