Add-ons/ShimsNightly

Status: this document is in progress

Thank you for using Firefox Nightly. Using Nightly is helpful because it provides improved feedback on changes being made in Firefox.

The Firefox team is currently focused on vastly improving performance in Firefox 57. Unfortunately, if you have add-ons installed in Nightly that are not WebExtensions, they make performance measurements on Nightly much harder. This is especially true of add-ons that are not multiprocess compatible and use shims.

As a result, we are asking all Nightly users to stop using add-ons that are not multiprocess compatible, or are not WebExtensions. Please bear in mind that these add-ons might stop working by Firefox 57 anyway.

If you've seen a message like this:

It means you've got some add-ons that are not multiprocess compatible or are not WebExtensions.

This restriction is reversible. To do so go to about:config, look for the setting:

extensions.allow-non-mpc-extensions

...and set it to true.

However, we'd like you to consider not reversing this preference. Leaving it set to false will give the Firefox performance team a much clearer idea of how much better we are making Firefox. Thank you for your help and support.

Tracking bug: 1352204

If your add-on has been disabled, have a look at https://developer.mozilla.org/en-US/Add-ons/Working_with_multiprocess_Firefox#Adapting_to_Multiple_Processes