TBF zstd runs most of the gamut, so depending on your settings you can have it run very fast at a somewhat limited level of compression or much lower at a very high compression.
Bzip is pretty completely obsolete though. Especially because of how ungodly slow it is to decompress.
Yep. But bzip2 is much less flexible; reducing its block size from the default of 900 kB just reduces its compression ratio. It doesn't make it substantially faster; the algorithm it uses is always slow (both to compress and decompress). There's no reason to use it when zstd is available.
Oh I completely agree, as I said bzip2 is obsolete as far as I’m concerned.
I was mostly saying zstd is not just comparable to xz (as a slow but high-compression ratio format), it’s also more than competitive with gzip, if it’s available the default configuration (level 3) will very likely compress faster and use less CPU and yield a smaller file size than gzip, though I’m pretty sure it uses more memory to do that (because of the larger window if nothing else).
I agree about the practical utility of bzip2. It's quite an interesting historical artefact, though, as it's the only one of these compression schemes that isn't dictionary-based. The Burrows-Wheeler transform is great fun to play with.
It does achieve higher compression ratios on many inputs than gzip, but xz and zstd are even better, and run faster.