FCP 2.06 came out about seven years ago! Is this what you are using? Other things to look at are the size of the photo's themselves. What is the resolution of these photos. With that many photo's on a timeline you should really try and keep the dimensions down. If these are 4000x3000 sized photo's you're in for a world of hurt when trying to render.
We need some more details to go on in order to offer up some useful help.
Michael Alberts
Ambidextrous Productions, Inc.
http://www.ambidextrous.net