After contemplating about responsive images - especially for my photo journal - I had a look at my current approach and whether it makes sense to add image variants in AVIF format to the mix. And my current answer to this is “no”.
First up, AVIF images do not support incremental or even progressive rendering, which is not optimal (although the potential file size savings could lessen this issue). Second, I would need to make sure all operating systems I build this site with have AVIF support (and at least one of them currently does not). And third, I would need to update the library I use to generate all those assets (because this would need image-format-converting capabilities). And that’s just too many downsides - at least for now.
Instead, I had a look at the quality setting for the JPEG conversion and see if I can reduce file size further. I tried this with a handful of my images; and indeed, I figured I could reduce the quality setting a little further without discernable difference to the displayed image (specifically, I reduced quality from “85” to “75”). This resulted in a file size reduction of around a third of the previous version, which is quite significant. I’m not going to re-generate all the historic assets (just now), but going forward all those generated images for my photo journal will be smaller in size. And with that improvement, I’m quite pleased!