I am managing two web sites with two different web hosting companies. Researched a lot to optimize them, and many article said this plugin is the best of best. So I applied it to my web sites. However, with some reason, it made my sites slower. I checked with P3 Plugin Performance Profiler, and W3 Total Cache used most of resource.
So I uninatalled it and installed the other one, it worked much better. I do not know why people praise this plugin so much.