Making Fewer HTTP Requests is #1 rule for improving performance for Web Applications according to Yahoo:
"Reducing the number of HTTP requests in your page is the place to start. This is the most important guideline for improving performance for first time visitors."
Here is how Fiddler 18.104.22.168 can help to identify number of requests that particular Web Page generates.
Fire up Fiddler and make sure it is capturing the Http traffic [it does by default] by looking into left corner in the bottom:
Then navigate to the page of your interest, yahoo.com for example. Fiddler captures all the traffic and presents it in detailed manner:
It is interesting to see how much traffic the page generates and the overall bytes received as a result of navigating to the page:
How to improve? Yahoo has nice set of rules here: http://developer.yahoo.com/performance/