This tutorial uses Scrutiny or Reactivity. The page test is a component of Scrutiny, but is also built as a standalone app called Reactivity.
You can get the same results from this online demo [link removed as out of date], which runs the same app but it doesn't have the user interface and the results are presented on a web page.
1. If you're using Reactivity you'll be presented with this window. If you have Scrutiny, call this window with Window > Page analysis, command-2 or switch to the SEO tab and press 'Full Page Analysis'.
2. Type the address of the page that you'd like to test and press Go. To test more than one page at a time, simply open another window - In Scrutiny repeat step 1. In Reactivity use File > New or command-N
4. Remember that the response time and load time will reflect the server's response time and speed, but will also be affected by the speed of your own internet connection.
5. You will see a total weight for the whole page. (The one in the example is a bit hefty). You will be able to spot any elements on your page which are particularly big, and you'll also be able to spot any elements which are slowing your page down - third party code or plugins often cause such problems and affect your page's response - maybe even your Google page rank.
6. If your site uses compression, then you'll see the compressed as well as the uncompressed size for each element as well as totals, and see how effective that is being.