Performance is important but often overlooked when it comes to building responsive sites. We often spend time discussing layouts, breakpoints, and designs that fits well for both desktops and mobile but we do not invest more time in thinking about performance. We learned this the hard way when we revamped Viki's main web page to a responsive site a few months ago. In the process of improving Viki's performance, we discovered practical techniques and useful tools in helping us enhance our user experience and monitor our performance. In this talk, we are going to share the present and the future of performance optimizations for responsive sites.