Sophos Support has had reports of Apple Mac OS systems where web browsing stops while Sophos is installed. Currently, this is under high priority investigation do determine the cause and correct the issue.
For more information, please refer to the below article:
I ended up removing Sophos Endpoint from my MacBook Pro because the slowness outstripped the value of the product. I really home that Sophos can turn this ship around and provide some quantitative changes that can be proven that this product is not slowing down all operations on the system. I was monitoring Activity Monitor every 30 minutes and EVERY time I reviewed my CPU hogs, Sophos was at the top chewing up greater than 50% CPU, sometimes pegging the processor on my 4 core i7 system. I finally decided that my battery life and performance was going to be worth the risk of removing the intrusive scanning/updating/whatever else this thing was doing in the background.
I've been a long time supporter of Sophos, but their rapid growth and acquisitions/feature creep feels like they may have run too fast and not optimized the code in the process.
Please give us some assurance that you're going to right this ship Sophos.
The workaround that we are currently deploying is to remove it from our machines. Nothing else helped.