How can I stop my game from lagging without getting rid of any thing.

I was using cutscenes alot in my game and it seems that it caused my game to lag. That's because it causes to many collisions at once.See each time the character would say somthing he would need a CS dialog and then the other character would talk and he would need one and then since the one character stoped talking to let the other one speak he need another CS dialog to continue talking and so that back and adding more CS dialogs causes more colisions at once it causes the game to lag.
heres an example of what it will eventually look like
http://dl.dropbox.com/u/34020769/part%203%20intro%20part%203.png

To have the story line I need those so I can't get rid of them. I optimized the game as much as I can so is their any way I can make my game faster without getting rid of them.

A few tips, that may or may not help

-Try not to have too many actors on screen.

-Delete anything not being used and off screen.

-Recycle things that are deleted and recreated.