Turning on Rocket Loader will immediately improve a web page's window.onload time (assuming there is JavaScript on the page), which can have a positive impact on your Google search ranking.
Automatic Mode: Rocket Loader will automatically run on the JavaScript resources on your site, with no configuration required after turning on automatic mode. Manual Mode: In order to have Rocket Loader execute for a particular script, you must add the following attribute to the script tag: "data-cfasync='true'".
As your page passes through CloudFlare, we'll enable Rocket Loader for that particular script. All other JavaScript will continue to execute without CloudFlare touching the script. (https://support.cloudflare.com/hc/en-us/articles/200168056)