Caught this beautiful firefox plugin, YSlow on delicious and thought it's worth mentioning here.
From Yahoo Developer Network - YSlow analyzes web pages and tells you why they're slow based on the rules for high performance web sites. YSlow is a Firefox add-on integrated with the popular Firebug web development tool. YSlow gives you
# Performance report card
# List of components in the page
# Tools including
JSLint
# HTTP/HTML summary