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

Firefox is unbearably slow after updating (/questions/985969)

  • 6 tontu
  • 9 am na jafe-jafe bii
  • 3 views
  • i mujjee tontu mooy alan_r

more options

Firefox slows down and raises my CPU to 100% after a few hours of use. This happened again and again after I updated Firefox to Versions 27, 28 and now 29. If I reboot my computer, Firefox works normally for a while before it slows down again. Even typing text on my email slows down to a crawl.

The 3 add-ons I have are as follows:- a) Adblock Edge 2.1.1 b) Download Youtube videos as MP4 1.7.18 c) McAfee SiteAdvisor 3.7.0

This is a serious problem and a game changer for Firefox. I hope the experts in Firefox will fix this bug soon. Meanwhile, if there is a workaround to this problem, would someone share his solution in this thread please?

Firefox slows down and raises my CPU to 100% after a few hours of use. This happened again and again after I updated Firefox to Versions 27, 28 and now 29. If I reboot my computer, Firefox works normally for a while before it slows down again. Even typing text on my email slows down to a crawl. The 3 add-ons I have are as follows:- a) Adblock Edge 2.1.1 b) Download Youtube videos as MP4 1.7.18 c) McAfee SiteAdvisor 3.7.0 This is a serious problem and a game changer for Firefox. I hope the experts in Firefox will fix this bug soon. Meanwhile, if there is a workaround to this problem, would someone share his solution in this thread please?

Saafara biñ tànn

Start Firefox in Safe Mode
While you are in safe mode; Firefox Options > Advanced > General.
Look for and turn off Use Hardware Acceleration.
Poke around safe web sites and see if there is still a problem. Then restart.


It could be the work of one of your add-ons, or even add / mal-ware. Look thru your add-ons list and make sure you know what each one is there for. Also, check the programs that are on your computer Windows > Start > Control Panel > Uninstall Programs. Go thru the list and use a web search to check any that you don't know what they are.

Troubleshoot Firefox Issues Caused By Malware

Jàng tontu lii ci fi mu bokk 👍 1

All Replies (6)

more options

Saafara yiñ Tànn

Start Firefox in Safe Mode
While you are in safe mode; Firefox Options > Advanced > General.
Look for and turn off Use Hardware Acceleration.
Poke around safe web sites and see if there is still a problem. Then restart.


It could be the work of one of your add-ons, or even add / mal-ware. Look thru your add-ons list and make sure you know what each one is there for. Also, check the programs that are on your computer Windows > Start > Control Panel > Uninstall Programs. Go thru the list and use a web search to check any that you don't know what they are.

Troubleshoot Firefox Issues Caused By Malware

more options

Thanks FredMcD for your quick advice.

I did not post a reply immediately because I wanted to test each step for a day or two first to see if my CPU remains at 100% after a few hours.

Whenever this happens, Firefox becomes unbearably slow.

The steps I have taken so far were:- 1) Restart Firefox in safe mode with hardware accelerator still on. 2) Restart Firefox in normal mode with hardware accelerator off. 3) Reactivate hibernate mode in computer. 4) All these while, CPU does not remain at 100% but fluctuates widely. 5) Reset Firefox to factory defaults with hardware accelerator still off. 6) Turn hardware accelerator back on.

My conclusion now is that those steps have solved 80% of this problem. Is FredMcD able to deduce what was the real cause from the actions I have taken? Does this also mean that I have to give up Adblock Edge 2.1.1 and Download Youtube videos as MP4 1.7.18 as they are no longer in my Firefox?

Further advice would be appreciated.

more options

I almost always download videos to watch later. This way I don't have to wait around for the clip to finish. You can always delete it later.

Have you checked this yet; Troubleshoot Firefox Issues Caused By Malware {web link}

more options

Same here. I will be disappointed if I cannot use Download Youtube videos as MP4 1.7.18.

Yes I checked out the link you gave but I do not have the symptoms described.

more options

Lets try this. Start the COMPUTER is safe mode. Let it sit for a while and see if there is any problem. After reboot, and let it sit there. Anything?

more options

I don't know what having two versions of Flash actually does(anyone?) but I suggest you remove the older one.