HTTPS Everywhere v. 3.x and 4.x hang firefox
IIRC I seen some info about this bug either in Changelog or after searching the internet about it, and it was related to the "new list in version 3" of the extension.
ISSUE: I tried upgrading from 2.2.3 to 3.0.x (all version up to 3.0.2) and also some of the 4.x version and same thing happens: firefox hangs at using 50% of the CPUs and starts to eat the RAM up to maximum, so I guess some memory bug is in place.
Even 'plugin-container' does not spawn and since the browser does not start the GUI I can not see any error messages.
I even tried a 'fresh-like' install: uninstalled the 2 version, cleared / deleted most of the settings from about:config related to HTTPS-E and tried installing the 3.x / 4.x extension. Same thing happens.
The profile I am using has A LOT of extensions so might be a conflict there. Also I am using the same profile since version 3.x of firefox...
Cheers.