I've found a page that isn't rendered correctly by Firefox with my usual profile. It is rendered correctly with a blank profile.

I have quite a few add-ons. One of them is surely the culprit. How can I find out which?

Userscripts often affect the rendering. But I turned off Greasemonkey, and it didn't help. So it's something else, presumably an extension (what else could it be? I have no chrome/userChrome.css.). I'm looking for an easy way to find out which one, easier than disabling a bunch of extensions and restarting umpteen times.

Related: Create a tool to help users identify a problematic add-on by bisecting the list of installed add-ons — a similar problem which would admit a similar solution. I want to automate this as much as possible; something like git bisect, that doesn't require me to change my actual profile, would be ideal. A Linux-specific solution is fine with me.