The header image in the article is a 2400x1600 PNG that is 500KB large, apparently due to subtle dithering making it hard to compress. Converting it to a visually-identical .avif (quality 90, 12-bit color depth) takes it all the way down to 15KB.

For an image which isn’t even interesting or illustrative of the issue. Hero images on blog posts have run their course, I can’t remember the last time I felt anything positive by encountering one. They make the page load longer, force us to scroll to start reading, and are forgotten as soon as they go out of sight.

Indeed, the website transfers 1.18mb (compressed) to deliver 6.7kb of text. Kind of ironic.

I'm guessing it could be even smaller if it was designed as a SVG file. Although the glow effect with the fading colors would probably need to be simplified.