I want to know too considering I have ALL disk caching disabled and all "disk" capacity entries are set to "0". No telling what's hidden though. Sessionstore interval is set to 1 hour so it's not that either.

Interesting note: I have only ONE mechanical harddrive for storage/archive only, it's 6TB, big and noisy. The other drives are all quiet SSD. My FF Profile is on a seperate SSD (seperate from OS, Applications, etc.) What does this matter? Because I always hear the big noisy 6TB drive ONLY when FF opens. This 6TB drive also happens to be my download directory for FF. But saving files or not this drive is constantly being accessed when FF opens. Again, my Profile is on a whisper-quiet SSD, so it's not standard read/write stuff to Profile items going on here. Seems like FF is constantly accessing this drive (the last download directory) for some reason immediately upon launching. Irritating as hell.

I cant swear on it but i think it started after i upgraded from 43 to 48.0.1, which version do you use proxy.socks?

Does the odd behavior occur in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Firefox in safe mode still reads alot.

On 48.0.1 and OS X 10.11.6.

And yes, it's been doing it through many versions. I've seen stuff posted about in a lot of places; stack exchange/overflow, github, ghacks, but no solutions.

Is it the OS? nsurl or countless other metadata or logging BS processes... I don't know.

Approximately reads 10gb an hour and write 1gb an hour today.

Proxy.socks, do you use any of these addons?

adblock plus bartab plus bookmark deduplicator cacheviewer download youtube videos as mp4 fasterfox lite greasemonkey with script for a certain forum liveclick privacy badger remove it permanently session manager tabs closebutton restored tabs on bottom websecurify youtube video replay

Add-ons:

• uBlock Origin
• New Tab Override (thank you Mozilla for making me to have to get an add-on for new tabs that won't show the world my browsing history)
• Tab Groups (thanks again, Mozilla. Pocket and Hello are so much more needed and practical)
• Toggle Animated GIFs (again, thanks Mozilla for removing the simple Esc key toggle)

Plugins:

• Flash Player