Thought activating this would be a good idea since it said it would speed up my system. Instead I found that activating the plugin and choosing Caching On in the admin setup made it impossible for my site to update after I made a change to it. I would even change the theme for the site and the site would still show the old theme. It is like the site just got stuck where it was, never to change. So, of course, I went back to my old settings with Caching Off. Not sure why you would ever want Caching On unless you had a site that never was updated.