Unresponsive Windows 10 laptop: automatic disk optimization

I have a 3-years old laptop at home (bought February 2015). HP, quad-core A8 CPU, 4 GB RAM, 5400 rpm HDD (slowish, I know). It came with Windows 8, then upgraded to 8.1 and finally to 10. It is used for browsing the Net and simple text and image processing. PCB design and Arduino coding, when needed. It has become less and less responsive without us adding new software. The symptom is the hard-disk being used 100% of the time without any apparent reason.

The problem lies in the user, or better, in the way we use it. This laptop gets used in the dark silent sleepy quarter-of-hours that lay between housekeeping chores (doing the dishes, getting ready for the next workday, ...) and hitting the pillow. That's between 23 and past midnight.

As far as I could understand, on Windows 10 I can define a "let me full control of the computer" time range, up to 12 hours long, but it doesn't span across midnight. Instead we need to be able to use it quickly, for 15-20 minutes in late evening, while Windows apparently does all its chores rendering the machine unresponsive.

So, before throwing it away in despair I wanted to try the move to Linux (Ubuntu): I've been using it as my main operating system at work in a 99% Microsoft-based environment, besides I know what I'm doing. Once I confirmed that everything apparently works booting off a USB drive, I needed some HDD space to install Ubuntu.

The correct procedure consists in shrinking the HDD though a standard Windows tool. That's when I saw the red alert light: Windows (10) is configured to do an automatic disk optimization once a week. On a 500 GB HDD full at 75% it could take half an hour. But what if in the meantime the antivirus updates, you use the computer and you shut it down because you're fed-updone? The whole process takes longer and I think it goes into an endless disk optimization, because it almost never completes.

Regardless this discovery I will install Ubuntu (16.04 LTS) on this HP 15-g005nl because there's no software keeping us tied to Microsoft Windows operating system.

Meanwhile, if you solved Win10 unresponsiveness due to 100% disk usage, let me know in the comments (and stay in-topic, I won't allow Win vs Linux flame or bad words about any of the products: tested solutions only).