FireFox browsers sometimes needs to be restarted again when you change theme or add an extension. This option is added at run time but in case you would like to restart FireFox browser manually, Quick Restart helps you to do a manual restart.
This Addon adds a Restart option in File Menu of the browser which is functionally equivalent restart of Automatic Restart option given by FireFox at certain times.
This is a very good option in case your browser is not responding properly or has become too slow, restarting can help you solve those problems. Install this Addon from here