I forgot to mention that it was an HP laptop that first had an issue.  I found some info in the HP Help Forums.  Here's a thread for a Windows 8 system:
 
https://h30434.www3.hp.co...asionally/td-p/4884899
 
 

What was weird, my laptop came with Win 8.1, which I upgraded to Win 10 last year.  Don't recall having this issue on Win 8.1.
 
I only noticed this 100% disk usage after the upgrade to Win 10.  Same hardware, same BIOS, same applications, etc.
 
If you open Resource Monitor and study the Disk Activity page, you can see the tasks and the file paths that are actively being read/written.
 
Typically I am only seeing low CPU use while pegged at 100% HDD by various processes for a period after boot.  Obviously a lot of concurrent read/writes going on.  Maybe developers these days just assume the majority of users are on SSD now, and code accordingly?

abacab
Maybe developers these days just assume the majority of users are on SSD now, and code accordingly?

Nah, that's like saying car stereo designers assume everyone drives a porsche.
What media the software is running on is just not a designer consideration in most cases.
 
Some activities such as modifying files are disk intensive or when your PC reboots and numerous programs are loading. That is normal. If it bothers you get a faster hard drive or an SSD.
 
The concern is when your PC shows constant non-stopping 100% usage.
In this case something is wrong and unless the problem is the harddisk itself (as opposed to let's say OS corruption) cloning the system and migrating to an SSD might not change things, it might instead lead to premature SDD failure.
 
 

TheSteven

abacab
Maybe developers these days just assume the majority of users are on SSD now, and code accordingly?

Nah, that's like saying car stereo designers assume everyone drives a porsche.
What media the software is running on is just not a designer consideration in most cases.
 
Some activities such as modifying files are disk intensive or when your PC reboots and numerous programs are loading. That is normal. If it bothers you get a faster hard drive or an SSD.
 
The concern is when your PC shows constant non-stopping 100% usage.
In this case something is wrong and unless the problem is the harddisk itself (as opposed to let's say OS corruption) cloning the system and migrating to an SSD might not change things, it might instead lead to premature SDD failure.
 

I guess maybe I should have been more specific.  The issue of 100% usage on HDD after startup is more of a bottleneck related to too many things trying to access the disk at the same time.  But it's not noticeable on my SSD equipped DAW PC Running Win 10.
 
The Windows devs at Microsoft could have changed the scheduling priorities for startup services and tasks in Windows 10, assuming that more powerful multi-core PC's are the norm. 
 
It has always been a balancing act between hardware capabilities and the software that runs on it.   It was only a few years ago that web browsers and Flash became so heavy that you needed at least a dual core CPU to stream YouTube video, even with enough RAM and a decent GPU.  Had to say goodbye to my single core stuff.  That's progress ... new code is always written to take advantage of the next gen hardware.

The previously linked Windows 8 thread points to a bunch of issues with the system page file.

I ruled out the system page file on my Win 10 laptop by disabling it and rebooting.  It runs OK with 4GB RAM and no paging.  It is still worth a shot to try and troubleshoot though, as all systems are different, and there are probably many possible causes for these symptoms.
 
My HDD was still busy after booting.  But once Windows settles down, everything runs smoothly. 
 
Hardware tests fine, no errors.
 
So in my case, it appears to be a Windows issue.  I'm just going to live with it, or upgrade to an SSD.  But since it's just a computer for traveling, and not my DAW, not that concerned about it.  Just wanted to share info with the OP, since it sounded very similar to his case.

There is always the possibility that Windows is downloading the next big update.  It's good about hiding THAT process when you try to find it.
 

I use the ol' "metered connection" trick to be absolutely sure Windows updates are not downloaded ... 

Abacab, your experiencd is very similar to mine although this laptop was win10 from the start. That said, the first I noticed it was after a big update (anniversary I think) and the problem persisted and is especially bad the first boot after a windows update. I have seen on other forums the idea that win10 is not friendly to spinning boot disks but I find that unlikely. Will check the tenforums.

Abacab, your experiencd is very similar to mine although this laptop was win10 from the start. That said, the first I noticed it was after a big update (anniversary I think) and the problem persisted and is especially bad the first boot after a windows update. I have seen on other forums the idea that win10 is not friendly to spinning boot disks but I find that unlikely. Will check the tenforums.