So I just shrunk the JS for my blog for most pages from ~85kb (uncompressed) to 1.61 kb (uncompressed) by getting rid of jQuery and instead writing my own JS a bit more verbose.
It might even be less effective than jQuery's implementation, but the time that is spend on download and compile/interpret jQuery should be worse.
You could also provide WebP images additionally to PNG images, and you could use pngquant for better PNG compression: pngquant --quality=65-80 filename
Compressing Shivering-Isles-Onion-Service-5-hops.png using these parameters resulted in 18 kB instead of 63 kB.
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