Firefox: “A web page is slowing your browser”

(Like many of my technology postings, this is really here for my own notes on problems I run into, the solutions I try and what works when. They are updated as I learn.)

To disable multi-process Firefox, do the following

Type about:config in the browser’s address bar.

Confirm that you will be careful.

Search for browser.tabs.remote.autostart.

Double-click on the preference. It should change from true to false. Restart the browser.