After uninstalling add-on on Firefox... I notice in about:config that the configuration for that particular add-on is still lying around. Does this affect the performance of Firefox since obviously I do not want the add-on anymore. Are such settings still being used by Firefox?

And, there's no such add-on that will help us "Clean up" such unwanted settings right (such like what a reg cleaner will do).

Thanks

You can just right-click on them and select Reset. Then afterwards they will be removed.

But then I have to do that one by one =X hundreds of them

How many addons did you uninstall?

You could manually edit prefs.js I guess.

It doesn't affect Firefox at all. If anything, it could cause a very, very slight increase in startup time. Probably in the .0001 miliseconds.

Haha alright thanks