Although it was much faster, I could not live without my extensions, so I went back down to version 2. Today, after a little searching, however, I found out how to force my extensions to work in the Beta.
I managed to get my favorite extensions ( Firebug, Better Gmail 2, Snipfire!, and Autcomplete Manager) working by following instructions from this post.
What you can do is open the configuration (about:config) in your Firefox browser, right click the list and create a boolean extensions.checkCompatibility option there. Set its value to false and restart the browser.
Awesome! Firefox 3 is SO fast!