restore interval write function of Firefox (and also Chrome) produces a lot of writings over the day, according to servethehome.com.
about:config and search for
browser.sessionstore.interval (given in millseconds)
This is by default set to 15 seconds and causes the high integrated written bits over a day - more 10th Gibibytes (GiB) per day..
I’ve set it to 30 minutes, so in my configuration
browser.sessionstore.interval = 1800000
Restart the browser and that’s it.