I tested Cloudflare with one of my "content-heavy" slower sites.
First I tested the WP site (of course I use WP) with the cache plugin W3 Local Cache. Without the plugin the pages would take about 8 seconds to load. With the plugin the pages took about 3 seconds to load. I did test new pages each time that have never been visited before so it was the first the Mysql db built each test pages.
But with Cloudflare that pages took less than a second!!!! :third: I mean they loaded up fast, I was freaking impressed. I didnt stay with Cloudflare because I dont know if and when their IP may be banned because of other users. There is something here, its a great service. Its super simple to setup even a newb can do it. Then all you do is change the name servers on the domain you want to the ones Cloudflare provides and wait till they propagate. You will be impressed, and if you're not, come back here and flame me.... I can take it... lol.
One of my clients sites is a Yahoo ecommerce site that loads slower than shit, and everytime I perform an audit on the site it tells me that pages load to slow. Which I assume is hurting his rankings a little bit. I'm going to to switch him over to Cloudflare and see how his rankings do and will report here later. So subscribe if you want to know how it goes.