Just a few minutes ago I was happily browsing the Ubuntu Forums and I stumbled upon a post about getting Ubuntu to run as fast as Arch Linux. In that post, the author mentioned this new (to me) web browser called Swiftfox, and I decided to find out if it was worth a download.
When I visited the Swiftfox website, I figured this was just an optimized build of Mozilla Firefox, but still I decided to give it a go. They have this small installer, that basicaly is just a small bash script, but its oh so very easy to use! You chose a build that suits your specific processor, and it will fetch it for you from the Swiftfox site, install it and add it to the Applications menu in Ubuntu. That's better than building Firefox from source!
Now it was the time to see if the optimization was real. After clicking the icon, almost a second after I had a nice Firefox windows with ALL the extensions loaded and working. It started way faster than the Firefox build that comes bundled with Ubuntu, way way faster.
All in all, I've found something that's even better and faster than the official build of Firefox. Give it a try!