gzip (or really DEFLATE) does actually come with a small predefined dictionary (the "fixed Huffman codes" in the RFC) which is somewhat optimised for latin lett

gzip (or really DEFLATE) does actually come with a small predefined dictionary (the "fixed Huffman codes" in the RFC) which is somewhat optimised for latin letters in UTF-8, but I have not verified that this is indeed what ends up being used when compressing individual lines of source code.