Zend certified PHP/Magento developer

MsMpEng makes computer unusable

Every day for the first 8 hours or so, my computer is unusable due to MsMpEng.exe taking 100% CPU while scanning my file systems for viruses (I think). I’ve already excluded a whole bunch of folders. Weird thing is that when I go to Settings and look at Virus and Threat protection, under Current Threats, it says Last Scan: today, 04:30, lasted 2h41m. Yet, here I am at 11:45 and MsMpEng is still pegging all four cores. ProcMon indicates that it is reading the filesystem a lot….
Process Explorer screenshot

One site I looked at suggested setting Affinity for MsMpEng, but I get Access Denied, even from an elevated Process Explorer.

Is there anything else I can try?