Sophos slowed MBP to a crawl

After installing and removing Sophos, my 2015 rMBP remains really slow when accessing the SDD. MATLAB beachballs doing the simplest things.
Has anyone experienced this? Any solution?

(I know it shouldn’t, but it appears this is what it has done.)

Update: Diskmark benchmark is about the same.

This is not normal.
What does activity monitor say?

To see a bit more detail open terminal and type “top” and press enter.
This will show you all the active processes on your Mac.

Sophos seems to selectively slow things down. I’ve uninstalled from my MBP. My iMac Pro wanted a Tamper Protection password, something that I don’t have, and that shouldn’t happen on Home Premium. I have to use this hacky uninstall script to get rid of it.
Unfortunately, I just subscribed for two years. I’ll leave it on my girlfriend’s MBP, as it hasn’t seemed to affect her (yet).
I’m very disappointed.