> bzip2 and xz are extremely slow to compress

This depends on the setting. At setting -19 (not even using --long or other tuning), Zstd is 10x slower to compress than bzip2, and 20x slower than xz, and it still gets a worse compression ratio for anything that vaguely looks like text!

But I agree if you look at the decompression side of things. Bzip2 and xz are just no competition for zstd or the gzip family (but then gzip and friends have worse ratios again, so we're left with zstd). Overall I agree with your point ("just use zstd") but not for the fast compression speed, if you care somewhat about ratios at least

In the LZ high compression regime where LZ can compete in terms of ratio, BWT compressors are faster to compress and slower to decompress than LZ codecs. BWT compressors are also more amenable to parallelization (check bsc and kanzi for modern implementations besides bzip3).

I'd argue it's more workload dependent, and everything is a tradeoff.

In my own testing of compressing internal generic json blobs, I found brotli a clear winner when comparing space and time.

If I want higher compatibility and fast speeds, I'd probably just reach for gzip.

zstd is good for many use cases, too, perhaps even most...but I think just telling everyone to always use it isn't necessarily the best advice.

why would one even care about compression speed on minecraft ComputerCraft machine?

size and decompression are the main limitations