Most of the Browser benchmarks on the web are things like "Browser X can do 90 gazillion operations per second while Browser Y can only do 300 bazillion operations per second". However these numbers don't mean much to your average users. They don't even mean that you can enter plain ascii text without having to wait for your letters to appear.
This benchmark instead attempts to answer the question: "What is the longest period that I can expect my browser to be completely AWOL, refusing to respond even to my simplest of commands". Even when playing a game, a delay of 20 milliseconds will not be noticed, so we do not try to measure time periods this small. Indeed delays of 200ms are probably acceptable. However if you are getting delays around 1000ms (one second) you probably already noticed that your browser is slow, and just want a number so that you can complain in greater detail.
The typical use of this benchmark is to load all the webpages you usually have open (gmail, facebook, whatever). Then click the start button. The browser will then log the longest pause in each ten second interval. All measurements are in milliseconds
You can save this to your local disk if you don't want to keep visiting my home page. Email questions and requests to gmatht at gmail.com.