NortonInternetSecurityBF 1.5.0

Mac OS 10.8.3 --  My Firefox 21.0 Add-Ons list includes a plug-in identified as NortonInternetSecurityBF.plugin.  My Firefox is running slow (I often have to wait for the pinwheel to go away) and using like 30% of my CPU time even when it doesn't appear to be doing anything. Mozilla says some plugins can cause problems for Firefox.  Mozilla says "For most folks the only plug-ins that are really useful are Flash and Silverlight. (and the “Mozilla Default Plug-in” if you see one). Unless you know you need it, go ahead and disable any other plug-ins in the list. This will probably help Firefox perform better and certainly keep you safer."  Do I need NortonInternetSecurityBF.plugin?  Could it be making Firefox run slower?

Mac OS 10.8.3 --  My Firefox 21.0 Add-Ons list includes a plug-in identified as NortonInternetSecurityBF.plugin.  My Firefox is running slow (I often have to wait for the pinwheel to go away) and using like 30% of my CPU time even when it doesn't appear to be doing anything. Mozilla says some plugins can cause problems for Firefox.  Mozilla says "For most folks the only plug-ins that are really useful are Flash and Silverlight. (and the “Mozilla Default Plug-in” if you see one). Unless you know you need it, go ahead and disable any other plug-ins in the list. This will probably help Firefox perform better and certainly keep you safer."  Do I need NortonInternetSecurityBF.plugin?  Could it be making Firefox run slower?