@Daved11 - I doubt very much that just because you see these (very normal) events, that it has ANYTHING relevant to your issue. Here is a description of the event; "Event 5379:
Credential Manager credentials were read. This event occurs when a user performs a read operation on stored credentials in Credential Manager"
So, just to be clear, ANY interface, or function that needs to check your account credentials via the Credential Manager before the function is allowed to execute (program/ap/api/DLL etc) will create this "OK" event.
Please post what your make/model of machine is, and what the Windows 10 level is. The easy way to do this is to right-click on the start icon (bottom left), choose "run" from the list, then key in winver in the command box. Post the version and OS build from the little window that comes up.
Also, what Anti-Virus program do you have, and have you been "persuaded" by advert clicks to add any (probably useless) "virus scanners" and Driver scanner checkers, that will "fight" for CPU and disk resources on your PC, and conflict with your actual anti-virus program?
I did notice my laptop, once it had updated to Feature Update 2004 (that means April 2020 ), the Windows Search Indexer became much more aggressive than before, and was running very actively for long periods. After a few hours, it settled down to normal. You can check what is running and taking up a lot of the CPU or Disk I/O by making intelligent use of the Task Manager. You can start that by right-click on any black (blank) space on the activity menu bar at the bottom, and choose Task manager from the list. When it start, let it settle down for about a minute, make sure you click on the "more details" link near the bottom left side if you have never run it before, then click on the "Processes" tab at the top. Check for any process or app/program using a high CPU% (more than 25% means a probable CPU core hog/loop). Post back anything running that you are not expecting to be running.