Came across this interesting, readable, thorough article on current developments in dictionary #compression for web content.

Enticing pullquote: "…YouTube JS download size for returning desktop users [shrinks] up to 90% compared to existing best-practice compression."

Also, thank you: "Please please don't treat this as a license to deliver even bigger piles of #Javascript."

Jump to the "Putting compression dictionaries into practice" section if you're short on time.

https://httptoolkit.com/blog/dictionary-compression-performance-zstd-brotli/