Help! The SWF slows down . Something wrong in the code?

I am currently creating my portfolio site and have decided to use a combination of loading files externally and having some content on the base site.

On the base site, I have a vertical slider navigation for previewing my recent work. However for some reason when I publish the swf., it plays back in an staggering way. If i place the code for the same effect on a fresh swf file without the background and buttons of my site, etc… it plays fine.

I was wondering if someone could check out what is wrong with my fla. code or that particular code. What is slowing down my swf ? The (fps) frames per second have been set to 30 and i always work with this speed because it allows smooother motion.

Please help. :red:
I hope I managed to explained my situation.

Download the source file here