My work laptops have had extremely poor performance with Mozilla Firefox’s default configuration. Tabs would frequently hang for multiple seconds so the browser was very frustrating to use. The solution was to disable Firefox’s Accessibility Services.

Go to about:config, move past the warning message, and then follow these steps.

Firefox about:config warning screen
The warning page that appears when opening about:config
  • Type accessibility.force_disabled into the search bar
  • Double click on the number if it is 0 (false)
  • Set the number to 1 (true)
  • Click the blue tick to save the setting
Firefox accessibility.force_disabled configuration setting screenshot
The configuration variable to change.

That’s it, you’re good to go.

Thanks to /u/Shiedheda on Reddit for finding this solution.