That almost seems like a internet access problem that is causing the stutter. What ISP speeds do you have? And what if any codec or addons are you using?

I think I have found the issue...Webm enabled true is causing the problem. It is a bug. On Chromium, webm works fine.

"webm enabled" where are you seeing this at? Is this a Addon or something else?

about:config media.mediasource.webm.enabled default is false...True is causing problem check youtube.com/html5

Hi,

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

You will need to restart Firefox for this to take effect so save all work first (e.g., mail you are composing, online documents you're editing, etc.,) and then perform these steps:

In Firefox 54 and below:

1. Click the menu button and select Options (Windows) or Preferences (Mac, Linux).
2. Select the Advanced panel and the General tab.
3. Uncheck Use hardware acceleration when available.
4. Close Firefox completely and then restart Firefox to see if the problem persists.

In Firefox 55 and above:

1. Click the menu button and select Options (Windows) or Preferences (Mac, Linux).
2. Select the General panel.
3. Under Performance, uncheck Use recommended performance settings. Additional settings will be displayed.

   

4. Uncheck Use hardware acceleration when available.
5. Close Firefox completely and then restart Firefox to see if the problem persists.

Did this fix your problems? Please report back to us!

If the problem is resolved, you should check for updates for your graphics driver by following the steps mentioned in these Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

If the problem is still there :

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

With media.mediasource.webm.enabled set to True...enabling or disabling H/W acceleration does not solve this issue.

ezee said

With media.mediasource.webm.enabled set to True...enabling or disabling H/W acceleration does not solve this issue.

Have you tried with the preference's value set to 'false'  ?

How about Safe Mode  ?

Any more specific messages in the Web Console?

• "3-bar" menu button or Tools -> Web Developer
• https://developer.mozilla.org/en/Tools/Web_Console

You can also try to set this pref to true on the about:config page.

• media.decoder-doctor.verbose = true

no such message https://youtu.be/p2qyLs8Ts4s