Tap here to go to the mobile version of the site.
Your Firefox is out of date and may contain a security risk! Upgrade Firefox

Support Forum

Intermittent video lag in Firefox


Firefox lags while streaming embedded and non-embedded videos, video comes out jerky while sound keeps playing smooth.

Either this problem gets solved or I figure out how to fix it or I'm switching to Chrome or back to Safari, neither of which has these problems. Gonna miss NoScript, though.

Additional System Details

Sites Affected


Installed Plug-ins

  • Gecko default plugin
  • Runs Java applets using the latest installed versions of Java. For more information: Java Embedding Plugin. Run version test: Java Information.
  • http://www.facebook.com/fbplugin/
  • BrowserPlus -- Improve your browser! -- http://browserplus.yahoo.com/
  • iPhoto6
  • DivX Content Upload Plug-In: Uploads DivX video in your browser!
  • DivX Web Player version
  • Java Plug-In 2 for NPAPI Browsers
  • 3.0.50106.0
  • The Google Earth Plugin allows you to view 3D imagery and terrain in your web browser.
  • The Flip4Mac WMV Plugin allows you to view Windows Media content using QuickTime.
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in web pages. For more information, visit the QuickTime Web site.
  • Shockwave Flash 10.1 r82


  • User Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv: Gecko/20100722 Ant.com Toolbar 2.0.1 Firefox/3.6.8 GTB7.1

More Information

The following has NO EFFECT whatsoever on my problem:
I've already adjusted this value (added a few zeroes at the end of the number) after reading about this "solution" - did nothing at all.
iMac, all software up to date

Xiah 0 solutions 1 answers

please help me with this problem .

westofcolumbus 1 solutions 12 answers

I also have this problem. I have tried setting browser.sessionstore.interval to a higher number, which helped somewhat, but did not eliminate the problem.

The lag tends to occur at points where the video changes rapidly, or there is a lot of movement within the video. Unfortunately, this means you often can't figure out what happens during the lag by watching before and after the lag. Stopping the video and replaying the lagged part rarely if ever solves the lag, and it always happens in more or less the same spot.

It's gotten to the point where I don't even try to watch most videos in Firefox. I watch them in Chrome instead. Hopefully this gets fixed in one of the bazillion new versions scheduled to be released this year.

Jan 1 solutions 6 answers

I have the same problem with firefox 11, too. After restarting firefox I can watch some videos without any problems but after some time the lag comes back. I read somewhere that these lags can be caused by add-ons or plugins. Did you tried a restart without add-ons? In my case it seems to be Speed Dial which causes the lag so I have it disabled at the moment. I have to do a longer test though to be sure...

Chris Ilias
  • Moderator
115 solutions 1064 answers

Hi AeroflySimDE,
You're replying to a thread that is over a year old. You should use https://support.mozilla.org/en-US/questions/new where volunteers can get more details about your setup.

Because this thread is so old and more people might start using it for their own questions, I'm going to lock it.