Running the latest version always now it's 16.0.2
The only tweak I do always when I first install FF is this one
to make sure I am always looking at the latest version of a webpage not some old content that was not automatically loaded when I visit the site.
One example being, when I visit www.majorgeeks.com
I usually tend to see software that is 1 or 2 days old until I hit CTRL + F5 to do a hard refresh, then I see the new content. This is bad web programming on their part but also this issue never happens with IE or Chrome