If you see that Windows built-in search components (any of several, including the Indexer, Cortana, etc.) are using a lot of your disk bandwidth, run this in an administrative Powershell:
Add-AppxPackage -Path “C:\Windows\SystemApps\Microsoft.Windows.Cortana_cw5n1h2txyewy\Appxmanifest.xml” -DisableDevelopmentMode -Register
It appears to reset or reload Cortana or a big chunk of it, and probably disable “Development Mode” too. One web reference stated that the above has to be run in a newly created local admin profile to work.
Also, if you’re in a former (or, God forbid, current) SBS environment, make sure the SBS client is removed, and make sure GPO isn’t automatically reinstalling it.