Mozilla plans to overhaul the way Firefox used handle third party plugins. With the recent Java Plug-in vulnerability, Mozilla is changing the way Firefox loads plugins. Which means that our much need plugins like Java, Silverlight and others will be disable by default. With the change, Mozilla thinks that it will help increase the Firefox performance and stability and provide substantial security cover to user, and at the same time handing over more power to users.
Now, Firefox will only load plugins when user grants permission on the pop-up or when the user had already configured Click to Play to always run the plugins on the trusted or approved website.
Moreover, Mozilla had strongly recommended their users to keep their Plugin Up to date. The can do same at https://www.mozilla.org/plugincheck/.
To know more about the change follow the below link.
Source: Blog Mozilla