Speed Number at the bottom of the COL Page

What does the speed number mean at the bottom of the COL page? 

The number at the bottom of the any COL page that loads on the computer shows how long it took the server to make the web page, from the time it receives the request to the time it sends back the final bit of the response. It does not include the time it took the request to go from the client machine to the server, the time it took the response to travel from the server back to the client machine, or the time it took for the client machine to render the web page. The travel time is dependent on the Internet connection between the client and the server: number of hops, response time between each hop, max upload and download throughput, etc. The render time on the client side takes at least two times as long in IE8 than in any other browser that we support, for example.

When the number on the page is large, it is something we can work on speeding up. When the number on the page is small, almost all other speed issues are out of our control. Large is anything over 3000ms.