[gdulli]

I agree. I'd be happy with launching firefox in a more lightweight non-web-dev mode for everyday browsing and then web-dev mode with all the extra tools and UI elements. The cool thing about that would be that the developer tools could be more tightly integrated with the UI because they wouldn't have to be hidden from the majority of people who would never need them.

[Excavator]

You can use Profiles¹ for that sort of stuff. about:config² is good for a somewhat complete list of components that can be enabled/disabled.

1: https://support.mozilla.org/en-US/kb/profile-manager-create-...

2: about:config?filter=.enabled

[canuckistani]

See also the profilist extension:

* https://addons.mozilla.org/en-US/firefox/addon/profilist