Ten years ago, increasing the performance of a website usually meant tweaking the server side code to spit out responses faster. Web Performance engineering has come a long way since then. We have discovered patterns and practices that make the (perceived) performance of websites faster for users just by changing the way the front end code is structured, or tweaking the order of elements on a HTML page. Majority of the experiments and knowledge has been around delivering content to the user as fast as possible.
Today, web sites have grown to become complex applications that offer the same fidelity as applications installed on computers. Thus, consumers have also started to compare the user experience of native apps to the web applications. Providing a rich and fluid experience as users navigate web applications has started to play a major role in the success of the web.
Most modern browsers have excellent tools that help measure the runtime performa