Note from 29 September 2022

I accidentally moved my hero image onto Cloudinary (who I also adore!). But, a less-optimised image served from the same origin is always faster than a more-optimised image from a third party. Self-host your static assets! csswizardry.com/2019/05/self-host-your-static-assets/

True!

But most images are currently not or badly optimized. 😔

They would benefit a lot from an image CDN: resize, compression, modern formats, etc.