My Sophos antivirus detected what it calls "SpeedSurfing", and my Google-fu is failing me. The Chrome extension it deleted was Boomerang for Gmail.
The Boomerang extension interacts with the Gmail website making lots of HTTP requests. That behaviour is usually associated with malicious extensions which attempt to exploit advertisement networks by simulating user clicks.
Sophos seems to have invented a neologism and does not seem to explain it even in their own documentation. You may try opening a support ticket.