Firefox shouldn't be that slow, plain and simple. There's an extensive set of tests that go into making sure that updates to Firefox either improve performance, or are performance neutral, and these have been in place for quite some time.

I do however think the update is related to the slowness, just not in the way you might think. Older extensions don't always play well when upgrading Firefox - it's possible that there is an extension that's not working correctly. Take a look at troubleshooting extensions and themes for some advice on how to tell if your issue is being caused by an extension.

Firefox hangs or is not responding - How to fix and Troubleshoot Firefox crashes (closing or quitting unexpectedly) are more general articles dealing with freezing and crashes - these may also help you.

You should also take a look at Troubleshoot Firefox issues caused by malware if you continue to have problems. Malware extensions and plugins can cause problems just like legitimate extensions and plugins - and are more likely to do so when upgrading because they tend to be poorly written.

my extensions are working fine and i have no malware, trust me i just did a scan yesterday its not that its the update firefox screwed it up big time

If you've already tried everything else, then follow this Troubleshoot and diagnose Firefox problems guide. It's a fairly comprehensive set of steps that systematically eliminate all the likely causes for problems with Firefox. If that's followed it should get Firefox running as good as new.

If that still doesn't help, then you can find old versions archived at http://ftp.mozilla.org/ but keep in mind that you may miss important security updates by going back to an older version.

For a quick start you could give another browser a try to make sure you have a Firefox rather than a computer problem. A computer memory check could also be helpful - another user may be able to help on this.

You could also get rid of any third party toolbars.