No problem here. Have you tried troubleshoot mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode

For some versions of Firefox I have the problem that the images are loading until the cache reaches 1GB. Then Firefox stops loading images on Facebook. This happend to facebook only. Images on other websites are loading.

I also have the problem w/ photos not uploading on FB. It will give a tiny text explanation of what the photo is. It doesn't happen all the time but when it does I move to Chrome and don't have any problem. However I like the set up of mozilla's home page and perks better so I wish this could get fixed.

Go to settings, search for cache, clear your cache, reload Facebook. Worked for me today.

https://support.mozilla.org/en-US/kb/fix-problems-images-not-show

http://kb.mozillazine.org/Images_or_animations_do_not_load

https://support.mozilla.org/en-US/kb/fix-video-audio-problems-firefox-windows

https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues

https://support.mozilla.org/en-US/kb/html5-audio-and-video-firefox

https://support.mozilla.org/en-US/kb/troubleshoot-issues-with-plugins-fix-problems

https://support.mozilla.org/en-US/kb/warning-unresponsive-plugin

Is this question still alive? There have been many reports since this one about Facebook. https://support.mozilla.org/en-US/questions/1362205#answer-1469087