thumbnail.so and kdeinit are using my HD and CPU too much

Hello.
I'm rendering a video with blender, using a browser with a streaming hd video and another browser with a lot of tabs, but everything is working smooth.
Then everything begins to get slower and slower, and I notice that the hard disk LED stays continuously on. This goes on to the point that my pc is quite unusable.

This has happened a lot of times, and I had always thought it was a matter of running out of RAM and swapping. Often to the point that I had no choice but to press the reset button. But this time I happened to have System Monitor open and I could see there were like 10GB of free RAM. So I opened Task Manager and found out that there were kdeinit and many instances of thumbnail.so using all my hard disk bandwidth.

Why is this happening? What is thumbnail.so? How can I avoid this?

Thanks a lot!

I would delete all your thumbnail files in:

~/.cache/thumbnail.so/QtWebEngine/Default/Cache

Wouldn't hurt to clear out the thumbnails from here as well:

~/.cache/thumbnails

There's no thumbnail.so directory in my ~/.cache/. I have cleared out the other one, let's see if it happens again.