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Firefox slow after update


After the Nightly update yesterday, Firefox has become very slow. Pages freeze and load slowly, and everything is choppy, including scrolling.

Additional System Details

This happened

Every time Firefox opened

This started when...

Firefox Nightly updated on 5/14

Installed Plug-ins

  • Shockwave Flash 11.2 r202
  • 5.1.10411.0
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Office Authorization plug-in for NPAPI browsers


  • User Agent: general.useragent.override;Mozilla/5.0 (Windows NT 6.1; rv:13.0a1) Gecko/20120217 Firefox/13.0a1

More Information

  • Top 10 Contributor
  • Moderator
10776 solutions 96973 answers

Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If the new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.


Helpful Reply

Thank you very much for the assistance. It looks like Ad Block was the culprit. Hopefully that will be fixed immediately, because I consider that to be an absolute necessity, and one of the biggest reasons I use Firefox. Thanks again! I'll hope for a fix soon.

  • Top 10 Contributor
  • Moderator
10776 solutions 96973 answers

Helpful Reply

You're welcome.

You can ask at the Adblock Plus forum.