This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

What is Firefox doing behind my back?

  • 3 replies
  • 2 have this problem
  • 9 views
  • Last reply by Hrvoje

more options

Hi! Sometimes Firefox is very slow. When looking in the Windows Task Manager I see it uses 99% of CPU. Memory usage is 148.260 K. What is Firefox doing? I have Windows XP Sp 3. Version 5.1.2600 Service Pack 3 Build 2600 Processor x86 Family 15 Model 4 Stepping 9 Genuine Intel ~2800 Mhz BIOS Version/Date American Megatrends Inc. 1012.001, 28.03.06 Total Physical Memory 1.536,00 MB Available Physical Memory 799,89 MB Total Virtual Memory 2,00 GB Available Virtual Memory 1,96 GB Page File Space 3,35 GB

Thank you for the answer! :)

Kind regards, H. Penavin

Hi! Sometimes Firefox is very slow. When looking in the Windows Task Manager I see it uses 99% of CPU. Memory usage is 148.260 K. What is Firefox doing? I have Windows XP Sp 3. Version 5.1.2600 Service Pack 3 Build 2600 Processor x86 Family 15 Model 4 Stepping 9 Genuine Intel ~2800 Mhz BIOS Version/Date American Megatrends Inc. 1012.001, 28.03.06 Total Physical Memory 1.536,00 MB Available Physical Memory 799,89 MB Total Virtual Memory 2,00 GB Available Virtual Memory 1,96 GB Page File Space 3,35 GB Thank you for the answer! :) Kind regards, H. Penavin

Chosen solution

hello, you could try the steps mentioned in Firefox uses too much memory or CPU resources - How to fix in order to pin down the problem.

Read this answer in context 👍 1

All Replies (3)

more options

Chosen Solution

hello, you could try the steps mentioned in Firefox uses too much memory or CPU resources - How to fix in order to pin down the problem.

more options

This useful tool is now available direct from Microsoft http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx

Once you rule out the obvious you may need to consider malware as a possible cause. See also this related thread for further suggestions

more options

Thank you, I believe that I solved the problem. :)