Dear Techie?

I recently revived my old laptop to use as a "kick-around" machine around the house for web-surfing.  I installed Firefox from their website and as soon as  did, my computer came to a screeching halt speed-wise.  I used to run Firefox on this machine with no problem, but it looks like this new version is causing problems.  Can I go back to my old version that I used and liked?

Sincerely,

Jane