High CPU and disc usage

I’ve been seeing a number of questions on CPU usage on reddit and now I’m really starting to get concerned myself. Kodi is using between 60-104% of the CPU and something is happening to the storage in my home drive. It’s shrinking by about a G a second and I can’t track down what’s eating it. It’s somewhere after the home directory. Restarting gives back much of the space but while Kodi is running it just slowly ticks down.

A few days ago I had it fill up the drive and I had some problems. Couldn’t ssh onto the computer lost a bunch (but not all for some reason) of the settings in Kodi. This has me a bit worried. gnome-discs says the drive is OK. What is going on?