“The size of the average web page of the top 500 websites has more than quintupled since 2003. From 2003 to 2009 the average web page grew from 93.7K to over 507K (see Figure 1), over 5.4 times larger (Domenech et al. 2007, Flinn & Betcher 2008, Charzinsk 2010). During the same six-year period, the number of objects in the average web page more than doubled from 25.7 to 64.7 objects per page. Longer term statistics show that since 1995 the size of the average web page has increased by 35 times, and the number of objects per page has grown by 28 times.”- http://www.websiteoptimization.com/speed/tweak/average-web-page/
There is a lot of information that can be had by analyzing what takes place when a web page is loaded into a browser. Not only information about what is being requested, time to response, size of objects, etc., but also how the server is setup in terms of caching, compression, CDN usage, and keep-alive information.
This postings looks at using an open source plug-in, AOL Pagetest, along with how to interpret the results.