Render-blocking resources are a common hurdle to rendering your page faster. They impact your Web Vitals which now impact your SEO. Slow render times also frustrate your users and can cause them to abandon your page.

"IntersectionObserver is a very straight-forward technology. It has a pretty good support in the modern browsers and if you want to implement it for browsers that still (or won’t at all) support it, of course, there is a polyfill for that. But all in all, this is a great technology that allows us to do all sorts of things related to detecting elements in a viewport while helping to achieve a really good performance boost."

"Quantum Render (or WebRender) is a major graphical system overhaul that’s coming to Firefox this year, and it promises hardware-accelerated painting of web content with huge performance wins."

"The result was a set of filters that whilst not vastly visually different, finally became interactive for more of our users as the loaded bundle was reduced to 53KB; a 70% reduction. Once gzipped that reduced further to 13KB."