NavyLCDR said:
What is the reason for doing scan health as a separate step before doing restore health? This is from the dism help file:

That seems to be saying that the scan health step is redundant because restore health is going to do the scan first anyway.

The scannow before restorehealth is to document the status of operating system corruption before attempted repair.

For example scannow may not be able to run, may run and display corruption that cannot be repaired, display corruption that was partially or incompletely repaired, etc.

It is only for documentation.

Some threads display a scannow with no integrity violations after a restorehealth.
The OP never gets any information that there was one or more problems that were fixed and could explain prior performance problems.

So as a routine I've run these commands in the above sequence so that OP can see the before and after.

For this thread I'd start with an in place upgrade repair:
Repair Install Windows 10 with an In-place Upgrade

The in place upgrade repair (same version) typically fixes operating system problems.
The in place upgrade repair (to an upgraded version) typically fixes operating system and registry problems.

So the in place upgrade repair can be ran more than once to have a better repair.

If that fails the OP can perform one of these:

a) reset save files
b) custom install
c) refresh Windows
d) clean install

Reset Windows 10
Custom Install Windows 10
Clean Install Windows 10
Refresh Windows 10

If there are partition problems or a desire to switch from BIOS Legacy / MBR ------> BIOS UEFI / GPT then perform a clean install.

The reset, custom, and refresh allow file saving while installing a fresh copy of Windows.