Had a problem with a "slow network" from a mac to a nas drive, was capping about 800mbit a second, despite having a 10g link.

As I looked through I killed sophos. Suddenly speeds shot up above 7gbit. A few seconds later they dropped back down, sophos has retured.

A "while (true) pkill sophos" later and the malware was sedated.

Having proved it wasn't a network problem I left it with the engineer to determine the best long term solution.