As of commit 9089c2d7 in the portage repo on git.overlays.gentoo.org, portage can now make use of the C wrapper to /usr/bin/install to copy extended attributes instead of the python wrapper. Since the C wrapper is much faster, this is preferred. Moving forward, portage should pull in sys-apps/install-xattr if USE=xattr is set. Reproducible: Always
portage-2.2.12 and later ebuilds pull in >=sys-apps/install-xattr-0.3.