Welcome. I used Ubuntu a few years, but eventually switched to OS X, not fixing for almost five years puzzle of Firefox on Ubuntu.
Regardless of whether you use the stable version, or test, scrolling the main page Facebook runs terribly slow. In Chrome and Chromium problem does not occur, but if it's my parents or friends, which I recommended system complain because they just prefer Firefox. Tell me what to do?
Naturally, the problem occurs on powerful and very weak computers, without distinction, whether the system is 32 or 64 bit. Currently, I see the problem in Ubuntu 14.04 LTS.