RESS merges Server Side Components with the Responsive web layouts. This method is not intended to focus on a full page optimization. It dynamically loads the content in accordance to the specific device on which the website is being rendered upon.
Example - if you are using a mobile phone with smaller screen resolution, then you don’t need a full size desktop image where you have to scroll your way to the desired content.
RESS is a life saver in terms of web page loading speed on responsive websites. As the more responsive elements you are adding the more heavier the website becomes.
RESS is a staple to every checklist related to mobile website testing.