It is quite old I think but I don’t know if it’s come up on the SDMB
What you do is paste it into the address bar of a particularly graphical website (lots of fairly small pictures) and press enter.
Be sure you have a reasonably good spec comp and that the website doesn’t have any huge-res pictures on it.
Below is a link to what it does to this page I’m using to compose this message. As I type and things are swirling around the page still works perfectly.