I already replied to a similar question here.

Have you enabled multi-process?

Additionally, you might tweak the value for browser.sessionstore.interval parameter in your browser.

Enter about:config in the address bar and click I'll be careful, I promise! when a warning about your warranty pops up.

Then enter browser.sessionstore.interval in the search bar. Double-click the parameter and change its default value (in milliseconds) from 1500 to a higher value.

This should allow Firefox to setup higher time interval for the browser to save a snapshot, so that it will use less RAM memory and videos will be played smoothly.

Let me know if you still have issues after performing these changes.

If none of these steps help, consider refreshing Firefox based on the below instructions:

The Refresh feature (called "Reset" in older Firefox versions) can fix many issues by restoring Firefox to its factory default state while saving your bookmarks, history, passwords, cookies, and other essential information.

Note: When you use this feature, you will lose any extensions, toolbar customizations, and some preferences. See the Refresh Firefox - reset add-ons and settings article for more information.

To Refresh Firefox:

1. Open the Troubleshooting Information page using one of these methods:
   • Click the menu button , click help and select Troubleshooting Information. A new tab containing your troubleshooting information should open.
   • If you're unable to access the Help menu, type about:support in your address bar to bring up the Troubleshooting Information page.
2. At the top right corner of the page, you should see a button that says "Refresh Firefox" ("Reset Firefox" in older Firefox versions). Click on it.
3. Firefox will close. After the refresh process is completed, Firefox will show a window with the information that is imported.
4. Click Finish and Firefox will reopen.

Did this fix the problem? Please report back to us!

Thank you.

Thanks. Is the multi process link current? I see it is from 2013. When I type the search in the "about:config" the closest results I get are browser.tabs.remote.autostart and browser.tabs.remote.autostart2

autostarts' status is "default" and value is "false" autostart2s' status is "user set" and value is "false"

I've changed autostart2 to "true"

The session interval is set at 15000, assuming the 1500 you stated is a typo, so I've increased that to 20000

Note that browser.sessionstore.interval is in milliseconds, so you are right about the increase to 20000.

When multi-process windows in Firefox is enabled then Firefox will use more memory and may be less responsive.

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/

1500 is the default value. I increased it to 150000, in fact the screenshot says user set.

If that was the default value, it would say "default".

As for the link to multi-process, my apologies. I meant to supply you with this, but I couldn't find it in my bookmarks.