Of course we all have seen this in some sort of a way, but I really would like to point something out, which took me very long to find the root cause. Also, I document it here for myself :) So any other PC which needs this fix, I know where too look.

This is such a typical Microsoft problem!

There are Desktop PCs and there are Lap tops. There are three (normal) ways to switch those off.

Shut down. This mode wants to close all windows and programs, and shuts the device down. Battery consumption is not zero, but it is low.

Sleep mode. This is the "moon" button on the keyboard, or for a Laptop, move down the screen on the keyboard, this also sleeps the PC.

Hibernate mode. This combines the above two. All information which is needed to reproduce the open programs "as is" , all open windows, and in fact the whole PC, "as is" will be stored at a reserved space of your disc. Then once done, the PC shuts down, but at a new boot, it will take all that data from the disc, and recovers your PC, with all programs and windows open, as it was. This makes no sense for a desk top, as saved energy is almost nothing. It makes sense for a Laptop, if you have such a situation, where you MUST have all windows reopened just the way they were before, AND you want to save your batteries, for instance you want to preserve your PC like that for more than a week. So even when batteries get empty after a week, if Hibernated, even after months, your Laptop awakes as it was, as soon as you recharged the batteries. So for the case you intend to do this, Hibernate it what you need. In all other cases, it is not, because is a terrible resources eater, and it slows down your PC very much, during normal use.

You think Microsoft configured this correct? What makes you sure this is so?

If you have allowed the Hibernate mode, you would not see it, unless you use it. Even if you never intend to use it, or do not know it exists even, still once activated, Hibernate is secretly active all of the time. It saves each and every little thing you do with the PC and the programs, and most of all, for each program it saves the actual way it was shown on the screen, each time you use "Enter" or Control "V". Where is this saved? The location is C:\hiberfil.sys

If you don't have such a file, your PC does not hibernate. However if you find it there, you just found the major resource eater of your PC. With my PC it was 12GB. Not only does it take 12GB, but also everything you do, gets saved in there. Suppose you use Adobe Photoshop. Each time you press Enter, all RAM data as it was in used by Photoshop, is stored into C:\hibernate.sys, and deletes the version before. So press the enter key triggers quite a big memory action, of which you see nothing, and you would never use it, unless you press "Hibernate". But the PC gets slow from this, much much slower.

How to delete the Hibernate mode.

In Windows 10, at the left bottom corner is the search window. Enter in there: POWERSHELL Then select: Open as administrator. So that shows a window similar to MSDOS.

Enter there the command powercfg h off. Like you see below.

Re-boot the PC to make the change active, and you are done.

Provided you had this file C:\hiberfil.sys before, it will be gone now, and you re-gained a lot of disc space. It was 16GB with my disc. Boot and shut down will go faster, and most of all your PC is much faster now. Well it is not really faster be itself, but things it has to do after you press "Enter" are now VERY much less. Oh, and Hibernate eats as much RAM space as it can get, and does NOT give the back unless you reboot. Needless to say, the extra RAM is an additional speed factor. Hibernate would eat 7GB Ram on my PC. Which is takes invisible. Very dirty process! So my PC has 16GB, but I was never able to use more than 9GB.

My advice: check for C:\hiberfil.sys. When you see it, do as above.