Comment by gwern

Sorting the files in an archive is a great trick to know for efficiency ( https://www.gwern.net/Archiving-URLs#sort-key-compression-tr... ); the more redundant your files are, the better it works and the savings can be enormous. Two near-duplicate files next to each other in a compressor's stream are basically free; space them by a few dozen megabytes, and you pay full-price...