CSS Stress Test
This project is a bookmarklet for stress testing the CSS on any given webpage.
It indexes all the elements and their classes, and then--class by class--it removes one, and times how long it takes to scroll the page. Selectors that save a considerable amount of time when removed indicate problem areas.
To install the bookmarklet, visit my blog post on this project: http://andy.edinborough.org/CSS-Stress-Testing-and-Performance-Profiling