CSS and the critical path – A talk by Patrick Hamann from The Guardian’s developer team
In this talk Patrick Hamann, senior client-side engineer at The Guardian, explains the importance of the speed of page rendering, prioritising critical CSS and how this is leading to and emerging “offline first” front-end build process.
To paraphrase the video’s description, the perceived speed of a website relies heavily on the browsers ability to paint to your user’s screen as quickly as possible. In order for this to happen the browser needs to construct a “render tree” made up of the DOM and the quite often overlooked CSSOM. This is the critical path and only thing which stands between your server and users screen.
Patrick covers a range of subjects in this talk, including why performance matters, the page rendering speed hurdles his team encountered when building the Guardians new website and what techniques they used to solve them. All of which leading to their goal of delivering the news to the user within 1000ms.
A very informative video with some techniques that we will be seeing more and more of as performance and “offline first” become more present in the web development landscape.