[mevile]

> extensions are also often the cause of a slow and frustrating Firefox experience

You have any recent data on this? I am not convinced this is true anymore.

[pluma]

This used to be a problem with legacy extensions because their APIs pre-dated the multi-process effort and forced Firefox into single-process mode.

In over a year of using Firefox every day I haven't noticed any slowdowns after Firefox made the move to drop compatibility for those extensions.

[kijin]

Extensions rarely cause slowness. Plugins (e.g. Flash) do.