Once upon a time, there lived a web developer who successfully convinced his customers that sites should not look the same in all browsers, cared about accessibility, and was an early adopter of CSS grids. But deep down in his heart it was performance that was his true passion: He constantly optimized, minified, monitored, and even employed psychological tricks in his projects. Then, one day, he learned about lazy-loading images and other assets that are not immediately visible to users and are not essential for rendering meaningful content on the screen.Original Source