I know that, but compression time is not as relevant as you think it is. If you look back at the measurements we did 2 years ago: https://lists.ubuntu.com/arch

I know that, but compression time is not as relevant as you think it is. If you look back at the measurements we did 2 years ago: https://lists.ubuntu.com/archives/ubuntu-devel/2018-March/040211.html https://lists.ubuntu.com/archives/ubuntu-devel/2018-March/04... You can see that the performance gain from zstd under realistic scenarios is about 10%. you can see that switching from xz to zstd only improved firefox install time from 37s to 33s; running in eatmydata to avoid fsync from dpkg improved it to 12.5s (8.5s with zstd). I don't know what Arch linux does, but they likely do not correctly fsync() data after its been written to a temporary file, and then fsync the directory after files have been renamed to their final names, as is required to achieve consistent results in a crash.