I have to disagree with his final suggestion, lazy loading images for a faster load. In my opinion, unless your page is extremely image heavy, lazy loading images causes more problems than it solves. It's a janky and annoying user experience every time I scroll a Medium post and have to wait a few seconds waiting for a big blurry square to pop into an image. I would much rather that stuff was loading eagerly and ready for me when I scroll.

Not to mention, knowing about their ecosystem, I shudder to think of the size of some of these JS libraries performing the lazy loading.