Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. The Firefox cache temporarily stores images, scripts, and other parts of websites while you are browsing.
Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies, do the following:

1. Tap the menu icon located at the top right corner. This is the icon with 3 bars. On older Android devices you'll have to press the hardware menu key and then tap More.
2. Tap Settings.
3. After that, you will be taken to the settings screen. In the settings screen, look under the section Privacy & Security and select Clear private data.
4. You will then be taken to a list of what can be cleared. Select the following 2 for deletion:
   • Cookies & active logins
   • Cache
5. After those have been selected, tap the Clear data button to actually clear the cache and cookies.

Did this help you with your problems? Please let us know!

see: Firefox for mobile is slow - How to make it faster

The solutions apparently did not work. I have locked the duplicate thread containing:

Didn't work. If anything it made it worse so, I tried uninstalling v.22, rebooting and reinstalling. Now I get an XML Parcing error when I try to get to Google news. Not too good. Now I'm afraid to upgrade my Win7 box! And please, no newbie canned responces this time. Its really annoying. 

I am rather new myself to Firefox Mobile so will see if others can answer

you could also try it with the firefox 23 beta version which is also available in the google play store and contains various improvements...