Asknobody
There is reason why you have to restart FF after instaling “classic” FF addons. They “may” integrate with FF to the level that normal use of FF without restarting would be impossible!
Check out JetPack addons, they do not need restarts!!! But you wont get as powerful addons as “classics”. But JetPack addons should work seamlessly on any FF version. (just like Chrome addons)
Migration to JetPack will take time (lots of it, since one addon can be writen for one of them but not both), and some addons simply need much, much, *much* more integration with FF.