If DISM /Online /Cleanup-Image /RestoreHealth appears stuck running the following can help with the feelings of impatience.

This will show the new actions as they are logged by DISM and re-assure you it's still going even if it's stuck at 62.3% for a while, especially when waiting for an under powered instance to complete DISM.

Get-Content C:\Windows\Logs\CBS\CBS.log -tail 10 -wait 

But when it comes to DISM on under-specced hardware, patience is the key. You might need to wait an hour or more for it to complete.