Until today, we were using old ThunderX1 aarch64 machines as kojid builders but today I replaced two (out of three) aarch64 with ThunderX2 machines (decommissioned from old koji.mbox setup used for stream 8 builds, now merged with stream 9 build infra), so clearly faster (not as fast as $currently available aarch64 builders but better than what we had previously)
See ticket : https://pagure.io/centos-infra/issue/1135
FWIW, we directly saw a faster build for samba today (see details in ticket). Should you encounter any issue, feel free to raise an infra ticket at usual place (https://pagure.io/centos-infra/issues)
Kind Regards,