Why is this widely used script killing my processor

I installed this popular, light-weight script on a website but it is running very poorly and maxing out my processor.

http://www.leigeber.com/2008/12/javascript-slideshow/

This is for sure my problem and nothing wrong with that script which runs fine for me on开发者_如何学编程 the demo site, but I have no errors and do not understand where the conflict lies. Any ideas on how to root this out?

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1. Install firebug
2. Find an action (e.g. clicking on a picture) that causes slow down.
3. Using firebug put a break point next to where that action starts
4. examine the code