Google released their new web browser, Google Chrome. It is much faster than firefox and internet explorer. Here's a link if you are interested. www.google.com/chrome
Been using it all yesterday and today. It's FAST, however the features are a bit lacking. Crashed on my a few times too.
From what I've seen, the speed is attributable to the JS improvements only. So on sites without a lot of JS, you won't see much change.
The good thing is that Google is open sourcing it all, so expect FF to have the same JS speed next year.