If you're seeing this in Big Sur, try adding the hosts to the M1 EAP program in your Sophos Console. That has resulted in better performance so far for us. You can add Intel Macs too.
Sophos is a nightmare for us this year. Their documentation on the matter has not helped us. BS 11.4 + EAP have, but it's a workaround and not a solution to Sophos' issues.