Even if certain plug-ins stops working, it’ll not affect your browsing. That’s a good move, but it requires additional system memory which may cause for slow browsing.
If you like to free-up this extra memory, you can simply disable the Plugin-container.exe, though not recommended.
Type about:config at the browser address bar and hit “Enter”. Click on “I will be careful, I promise”.
Now search for ipc in Filter box and locate the following five entries.
Right-click on each entry and click Toggle to change the value to False and vice versa.
Restart Firefox browser. Now plug-in–container is completely disabled for Firefox browser. (via)