[Bulat_Ziganshin]

1. both lzip and xz are using lzma compression library internally, so there is no difference in their compression ratio/speed

2. lzma compression is LZ + markov chains, while zstd is LZ + order-0 entropy coder (similar to zlib, rar and many other popular algorithms)

markov chains are higher-order entropy coding, i.e. one using context of previous data. it's slower, but sometimes gives better compression. but text files don't get any benefit from it. OTOH, various binary formats, like executables or databases, get significantly better compression ratio. in my tests lzma-compressed binary files are ~~10% smaller on average.

so, many claims that zstd and lzma provides the same compression ratio, are based on testing on text or other files that don't benefit from higher-order entropy coding. of course, I imply maximum-compression setting and equal dictionary size, in order to make fair comparison of compression formats rather than particular implementations.

(I'm author of freearc and several LZ-based compressors, so more or less expert in this area :)