Squashfs decompresses on the page-fault path through a single stream
(CONFIG_SQUASHFS_DECOMP_SINGLE), where xz manages roughly a tenth of zstd's
throughput, and the live root is read cold on every boot: kernel, plymouth,
systemd, python, archinstall, gum. The offline mirror is already stored
uncompressed, so this only covers the part that still gets decompressed.
Costs well under a percent of ISO size. Dropping the x86 BCJ filter also
removes one of the blockers listed in plans/aarch64-support.md.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
