Slow computer troubleshooting

Here's the list of things I do when troubleshooting a slow computer:

1) Run a malwarebytes scan and remove anything found
2) Install all applicable driver updates
3) Run "sfc /scannow" from an elevated command prompt
4) Install all applicable Windows updates
5) Install all applicable Office updates, if installed separately (true for some versions of Office 2016)
6) Check amount of free disk space (ideally at least 20 GB free)
7) Check for adware/crapware that is installed.  Remove by normal add/remove programs
8) Check CPU usage and disk usage for conditions above 99%

Using DISM to repair WIndows when sfc /scannow can't repair Windows 10

I have found that sfc /scannow doesn't repair system files on Windows 10 in many cases.  Sfc /scannow will find problems but not repair them.

I have found a fix that won't work for the average user - only sysadmins with access to a Windows 10 ISO.

Here's what I did:

• Downloaded the Windows 10 Pro 64 bit version 1511 ISO from "Microsoft Volume Licensing Service Center" - this 4 GB file will take a while to download
• Mounted the ISO file as d:
• Ran this command from an elevated command prompt:
  DISM /Online /Cleanup-Image /RestoreHealth /source:WIM:d:\Sources\Install.wim:1 /LimitAccess
• Re-ran "sfc /scannow" after the DISM command above finishes