Let me enlighten you, O seeker of wisdom!

I use waifu2x caffe to both denoise and enlarge the image, then I put it through pingo to reduce the file size as much as I can.

not sure what you mean by recursively optimize.

i use imagemagick, which does about the same thing caesium-clt seems to do - it's a command-line tool with relatively similar syntax. documentation is a little obtuse, but once you figure out what you're doing it's very powerful.

if you'd rather use a GUI tool, i use pingo as well. only thing is this one optimizes files in-place instead of moving them to another directory.

You can use tool like https://css-ig.net/pingo to further compress the PNG.

Also since the image thumbnails may not be the main point of focus here you could reduce the PNG to indexed colors. The images will get color banding but the text stays crisp and file size is reduced significantly.

Good tips, but he left out the oldest one in the book.

Optimize the images to reduce their filesize.

Pingo is the best image optimizer I know of. I use Pinga personally - the GUI version of Pingo.

It's fast, free and most importantly it optimizes the best.

The developer is currently also working on making it support AVIF and JPEGXL (the next big image format which should be even better than AVIF)

>ImageOptim

Thanks! i did another resize, and found the windows version of imageoptim, called Pinga. my city maps are now at 10 MB. and still very usable

https://css-ig.net/pingo