Disk becomes VERY slow intermittently, otherwise is fine (?!)

I tried to google it before asking clarification but it didn't help.

Here's how to do that:

dalchina said:

,,,,,,,,,,,,,, @jumanji - any thoughts? Thanks!

The OP may download bootable Partition Wizard ISO, create a bootable flash drive Using Rufus, boot into it and run Surface Test. This will determine whether the HDD is good or developing defects - bad sectors.

Partition Wizard ISO:
Bootable Partition Manger | MiniTool Partition Wizard Bootable Edition (Thanks to Bree for the waybackmachine)

Rufus: Rufus - Create bootable USB drives the easy way

I wonder then if any issue with Windows itself is to be excluded completely?

Whilst you could have a play with a live boot disk (i.e. independently of the O/S - which you also mean you could run a surface scan) - absence of the problem would not be definitive proof that it was a Windows issue.

However, that it occurred in Safe Mode suggests it occurs readily.

Try Hard Disk Sentinel just to see if anything is picked up.

Will do, thanks

One last thing, before the PC had any issue I moved a large folder (something like 60 GB of various stuff) which went well and I'm not sure if there might be any correlation with the disk issue; however, after the cut/paste procedure ended I noticed that while the vast majority of the stuff had the creation date unchanged, a few folders had their creation date changed to the cut/paste time.
Didn't think much of it at first, but now I'm thinking I could try to delete those folders to see if they got corrupted in some way which makes the disk go nuts. Does this theory make any sense?

fra said:

Will do, thanks

One last thing, before the PC had any issue I moved a large folder (something like 60 GB of various stuff) which went well and I'm not sure if there might be any correlation with the disk issue; however, after the cut/paste procedure ended I noticed that while the vast majority of the stuff had the creation date unchanged, a few folders had their creation date changed to the cut/paste time.
Didn't think much of it at first, but now I'm thinking I could try to delete those folders to see if they got corrupted in some way which makes the disk go nuts. Does this theory make any sense?

No. A check disk /f is to fix logical errors on the file system.
I still think that there is a problem with your HDD.
Read Chkdsk Log in Event Viewer

If you'd been using 3rd party disk imaging routinely (in particular Macrium) you would already know the answer to that.

Why? When a disk image is created, Macrium does a CRC check for data integrity as it scans. In one case that flagged early failure of a disk, detecting the problem starting to occur since the previous image.