Disk running at 100% – Windows 10

I recently had a user bring me an almost brand new machine that was running slow – upon my investigations, I found the disk running at 100% despite nothing running.

The machine was a 9th Gen i5, with 8GB RAM and an SSD, so should not have been slow. I checked the usual culprits (startup items, incorrect drivers etc) but it turned out the disk usage was showing at 100% and nothing was really running.


After some trial and error I came across this:

It turns out, in Windows 10, disk defragging (or “drive optimisation”) is scheduled to run weekly by default. I turned this off, and instantly the machine was running perfect.

It’s simple to disable this running automatically and shouldn’t really cause an issue:

1. Open file explorer and right click on C:.
2. Go to “Properties”, and you’ll get the below.

3. Click “Optimise” (above) to see the following.

4. In here, remove the tick from the first box, then press OK then close.

That’s it! You should notice an almost immediate increase in performance. You may need to reboot your machine, however in my case this wasn’t necessary.

If you’re interested in more info about disk defragmentation in Windows 10, Microsoft have an article on it here.

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