I can highly recommend these tools and if combined will make a difference to any website performance. I’ve included a couple of IIS flavour web performance tools below – a platform which isn’t that widely support for killer web performance. Anyway here’s the list – enjoy. Rich
It’s out of beta and looks great, here’s a (worthwhile) 1hr video on mod_pagespeed – expect Google to improve on this in the coming months.
2. ControlJS http://stevesouders.com/controljs/
[excerpt from Steve's page]
But basically enables you to start the DOM execution earlier.
3. http://requestreduce.org/ Instantly make any ASP.NET website faster with almost no effort!
This module does auto spriting, minification and bundling all at runtime – developer friendly. But as you never get ‘owt for ‘nowt be interested to see the server load.
4. http://www.webpagetest.org/ Run a free website speed test from multiple locations around the globe using real browsers (IE and Chrome)
great site which is fast becoming the defacto standard for RUM, you can install a privately hosted instance to test your website over time. It’s like a server side firebug but you’re able to select a worldwide location and browser