I've been having the exact same problems. Been trying to use Firefox primarily for the past few months but it gets frustrating having to restart it all the time.

Sounds like ghost windows. Try disabling all your add-ons to see if the problem persists? You can also record a profile via perfht.ml and send it to me, I'm happy to have a look.

Admittedly, my own experience was with older versions up to 57, but what it felt like e10s did not really help with responsiveness, especially after very long sessions (24 hours+). Restarting Firefox used to be a daily ritual (with all the lost website state that entailed) as JS pauses started becoming very noticeable. Fx would also keep the CPU in high power states with constant 10-20% CPU usage near the 24 hour mark.

I don't know if it's an architectural limitation of how e10s was implemented, but Firefox still feels like a single-process browser. On the other hand, Chrome remains responsive even after a week of being open.

Thanks for offering to take a look! What is your email? Next time it happens I'll be sure to send the logs along.

See what happens when you switch to Nightly Firefox.

FF has had performance problems for years. I doubt the magic fix is right around the corner.