I had tried everything to get W3 Total Cache to make a difference with my shared-hosted WP blog, but I kept getting no improvement. I finally followed the tutorial here:
http://gtmetrix.com/wordpress-optimization-guide.html
My blog page went from 78/69 to 100/100. I stand amazed. I went from a 3.63 second page load time to a 0.35 second page load time. I'm sold now. Thanks for a great product! :)