I'm using Firefox 5.0. It's definitely faster than the version which you're using.
If you do download it, you'll probably find yourself asking where the buttons which stop a page loading, or refresh a page, have gone to. (I write that because lot's of people have asked about the 'missing' buttons already on here!). All that has happened is that a single button now performs several functions. When you type a URL into the address bar, the button to the right of the bar will show a green arrow. (So, as usual, you click on it - or just hit 'Enter' - to go to the page you require). While the page is loading, the same button turns red an, if you click on it, performs the 'Stop' function. Once your page has loaded, the button goes white, and becomes the 'Refresh' button.
Chris