Flash is slowing down after while

I have a gallery flash that loads a pictures from xml. The pic slides on from the right. When btnNext is clicked it slides off to the left and the next pic slides on from the right. There is also a btnBack which slides on the previous pic. There are around 200 pictures.

I have now spent weeks on and off trying to figure out why it slows down and starts to chug! I figured out, with the help some other help, how to remove the pictures when they are off stage. It definitely helped but its not yet resolved.

This flash is quite processor intensive with the amount of graphics. But the thing is, when the flash start off it goes fine but after so many pictures it starts to chug. Which seems to me that there is somehting it is not GCing or something of the sort!

As I am quite new to programming I am looking for an experienced programmer who would be willing to look at my programming and see if you can spot where I am going wrong!

I know this may be asking for a lot and I don’t expect that anyone would just jump on it and do it - but if you could take a look it would be a great deal of help!

I have attached a CS4 AS3 file and notepad file.