I was noodling around on the react.dev homepage today, taking screencaps for a presentation I'm putting together. I had dev tools open and I noticed something odd: every time I would hover over a link, something would get fetched over the network. "That's odd, and quickly adding up to megabytes of bandwidth", I thought.

So I looked at the fetches being fired, and it appears that the website is preloading the content of the page being linked when you hover over the link. Any link, every single time.

Let me say that another way: on react.dev, every onHover over a link costs the user between 5kb and 10kb of bandwidth every single time.

I feel like I'm losing my mind. Forget the fact that this website costs 2mb to download and takes 23 seconds to complete loading, how can charging the user and the app for every hover over a link be sustainable? How is this appropriate?