Note: Also seems some videos do not load or play. Youtube is working fine though.

Try to move the current Firefox version to the trash and install a newly downloaded fresh Firefox copy.

You can find the latest Firefox release in all languages and for all Operating Systems here:

• Firefox 17.0.x: http://www.mozilla.org/en-US/firefox/all.html

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can also try to reset Firefox.

• https://support.mozilla.org/kb/reset-firefox-easily-fix-most-problems

If you reset Firefox then a new profile is created and some of your data (bookmarks, passwords, cookies, form data) is automatically imported and your current profile will be moved to the desktop (Old Firefox Data).

You can recover more data from the old profile (be cautious with doing that).

• http://kb.mozillazine.org/Firefox_crashes
• https://support.mozilla.org/kb/Firefox+crashes

If you have submitted crash reports then please post the IDs of one or more crash reports that have this format:

• bp-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

You can find the IDs of the submitted crash reports on the about:crashes page.

• You can open the about:crashes page via the location bar, like you open a website.

See:

• http://kb.mozillazine.org/Mozilla_Crash_Reporter
• https://support.mozilla.org/kb/Mozilla+Crash+Reporter

I've already re-installed it, and the old firefox info was moved to the desktop as you mentioned. However this still hasn't solved the random crashes and very slow or non-responsive loading on videos. For example if I click on a download for something like a pdf, and cancel, firefox crashes. If I download something and then close the download window in firefox, it crashes.

*UPDATE* Possible Fix? So after another crash loop I had to reset the browser (again) and this time it gave me an error saying it could now not find the profile.

So on my mac I moved the original firefox folder from Application Support onto the desktop and did a clean install of firefox. After the clean install I went into the new firefox folder, into the new profile and deleted the content inside. Then I copied all the content from the desktop firefox folder profile (not the profile folder itself only the contents inside) into the new profile. Reopened firefox and all my bookmarks, browser history and plugins are there. Downloaded a program, as well. No lag, freezing or crashes so far!