I wrote Yellow Lab Tools. It's an online tool hosted here: http://yellowlab.tools

It's designed to help developers speeding up page loading time and one of my main concern is the number of DOM reading/writing. Some heavy websites do more than 5000 DOM access on page load and developers/maintainers of these sites don't realize there is a problem.

To help people audit and analyze this problem, my tool has a "JS Timeline" tab, that logs DOM access during page load. The reason I write on this jQuery board is because I made YellowLabTools understand and log jQuery functions too:

 - it spies every jQuery function that's capable of reading or writing the DOM.

 - it helps you understanding what jQuery does internally by displaying sub-function calls.

 - it helps  detecting unused code (there's a red warning when a sizzle call returns no result or when a function is called on an empty jQuery object).

The tool is also able to detect if jQuery is loaded more than once on a page (it happens much more often than you may think), and many other non-jQuery related problems.

Test it and tell me what you think about. Tell me any idea you've got to help people optimize their jQuery code. Tell me everything!

By the way, it's open-source and it's free, so don't hesitate to share the tool if you like it ;)