A Netflix Web Performance Case Study

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Netflix is one of the most popular video streaming services. Since launching globally in 2016, the company has found that many new users are not only signing up on mobile devices but are also using less-than-ideal connections to do so. By refining the JavaScript used for Netflix.com’s sign-up process and using prefetching techniques, the developer team was able to provide a better user experience for both mobile and desktop users and offer several improvements.

Loading and Time-to-Interactive decreased by 50% (for the logged-out desktop homepage at Netflix.com) JavaScript bundle size reduced by 200kB by switching from React and other client-side libraries to vanilla JavaScript. React was still used sever-side. The area optimized for performance by the Netflix developers was the logged-out homepage, where users come to sign-up or sign-in to the site.

This page initially contained 300kB of JavaScript, some of which was React and other client-side code (such as utility libraries like Lodash), and some of which was context data required to hydrate React’s state. All of Netflix’s webpages are served by server-side rendered React, serving the generated HTML and then serving the client-side application, so it was important to keep the structure of the newly-optimized homepage similar to maintain a consistent developer experience.

Source: medium.com