Thanks! I think most of the weight comes from the PNG diagrams, but I don’t actually know: I’ll put it on my to-do list to investigate, maybe there are some easy wins here.
Claude was able to optimize the hell out of one of mine, might be worth a try
The ~750 pngs are about 15 megabytes. The 77 photographic images are 22 megabytes.
Somewhat a death of 1000 cuts.
I used https://www.xpdfreader.com/pdfimages-man.html to extract them and take a look.