Firefox CPU usage

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Revision as of 18:44, 5 February 2007 by SteveChapel (talk | contribs) (→‎Hardware Acceleration: add suggestion to disable hardware acceleration)
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Sometimes Firefox uses excessive amounts of CPU as reported by Windows Task Manager or by the top command on Linux.

Excessive CPU on certain web sites

If Firefox uses lots of CPU on certain web pages, please report the problem using Help -> Report Broken Web Site. Usually there's executable code on the site that is consuming the CPU. On the other hand, if a bug in Firefox is causing the excessive CPU usage, this will help track down the problem.

The Flashblock extension can help the problem by blocking Flash code that consumes excessive amounts of CPU.[1][2]

Sometimes JavaScript on some web pages can cause excessive CPU. You can use the NoScript extension to block execution of JavaScript on problematic pages.

Extensions

Some problematic extensions can cause excessive CPU usage. See the linked article for which extensions cause this problem and possible workarounds.

Hardware Acceleration

There are some reports that disabling cursor and bitmap hardware acceleration on some video cards and drivers can reduce CPU usage when displaying images.[3]

Windows Compatibility Tab

There are some reports that Firefox can cause excessive CPU usage if it's set to run in compatibility mode for an older version of Windows.[4] To fix the problem, right-click on the Firefox icon you click to start Firefox, click Properties, click the Compatibility tab, make sure the check box under Compatibility mode is unchecked, and restart Firefox.

Adobe Acrobat

Sometimes viewing pages with Adobe Acrobat can cause Firefox to use excessive amounts of CPU. This problem may be fixed by creating a WWW_OpenURL directory in the AdobeUM directory.[5]

Other causes

  • Read the Firefox hangs article for other solutions to Firefox consuming lots of CPU.
  • If none of the solutions on these pages fixes your problem, you may want to file a bug report. This is a list of unsolved bugs in Firefox that cause excessive CPU usage. Look through the list, and if your situation doesn't match any of the situations listed, file a new bug report. If you cannot give a set of steps that reproduces the problem, you may want to try to find a regression window to determine which change to Firefox caused the problem. If you're running Windows, you may also want to use Process Explorer to determine which thread is using most of the CPU and include this information in the bug report.