is that not the new update? did you recently update before you started having problems like this?

in dev edition its already a fact. and mozilla might be using more cpu and less ram this way with the upcoming updates

When multi-process windows in Firefox is enabled then Firefox will use more memory and may be less responsive. You may see extra Firefox content instances running (1-4).

You can try this to see if it has effect:

• set dom.ipc.processCount to 1 if it is currently set to a higher value (4)
• disable multi-process windows in Firefox

You can disable multi-process windows in Firefox by setting these prefs to false on the about:config page.

• browser.tabs.remote.autostart = false
• browser.tabs.remote.autostart.2 = false

You can open the about:config page: via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

• http://www.ghacks.net/2016/07/22/multi-process-firefox/

Just because your fan runs louder doesn't mean any harm is being done to your computer. That's a normal function and shows it's doing it's job. Have you ever tried blowing out your computer with a little compressed air? might do the trick.

Also, update Windows and make sure you install any Graphics Driver updates (they may be under Recommended or Optional)

maybe you have a heat problem developing. Boot into the BIOS, go into the temperature area, watch it for 5 minutes while on idle and if it gets above 50C, then time to replace the thermal paste on the CPU.

These last two comments don't seem to deal with what is actually happening.

Firefox 57 causes multiple instances of Firefox to run, which means the computer heats up so causing the fan to run overtime. If you CTRL+ALT+DEL and then shut down the multiple instances, then restart Firefox, the heat will return to normal and the fan will stop running like crazy.

But this is only a short-term solution of course.

What the real solution is, I have no idea. I'd like to learn more from cor-el about the effect of disabling multi-process in windows. Positives? Negatives?

hmmmmm