@a1ba was very surprised by tests with orz (a rust crate) against zstd and orz is very competitive (within a few percent in output side.) considering the algorithmic complexity of orz is so much less.

rolz is basically a chain of linked lists, using a very small rolling hash window to pick a slot. then it looks at prior findings at that slot, and emits a code for like "take the current hash slot, walk the back pointer 4 times, copy this many bytes." (the 'restricted offset lz' part.) orz then just feeds that through huffman. LZ and Huffman are incredibly cheap things with hardware support, too.

zstd requires arithmetic coding which is ass to work with.