WP Fastest Cache is Doc’s recommended plugin for WordPress when using CloudFlare. Despite the increased speed CloudFlare gives your site, WordPress still has to generate each page dynamically.
Above average visitor load can cause database connection timeouts. And even get your site shut down if on shared hosting.
You can gain a ton more website speed by caching your posts, pages, tags, and categories. When caching your site a generated html page is delivered to your site visitor. This saves WordPress from doing all the work saving bandwidth and server resources.