- Switch squashfs compression from xz to zstd (3-5x faster compression, ~10-15% larger but decompresses faster at boot) - Stop rm -rf BUILD_WORK_DIR on each build; rsync only config changes so lb can reuse its chroot across builds (skips apt install step) - Keep lb-packages cache in CACHE_ROOT as fallback if work dir is wiped Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>