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Firefox is unbearably slow after updating to version 27

  • 81 replies
  • 606 have this problem
  • Last reply by petef

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After updating to Firefox 27 all webpages take a few dozen seconds to several minutes to load. When loading a webpage Firefox's status displays "connecting" and the CPU gets maxed out with 95 to 100% of its cycles taking by Firefox.

The computer is older so it is a little slow but Internet Explorer 8 has no trouble opening the webpages and neither do other computers on the LAN so it is not a network issue. I have tried restarting Firefox, disabling add-ons, deleting add-ons, disabling hardware acceleration, restarting the computer, and reinstalling Firefox after wiping every trace of it and its user data from the hard drive and registry.

CPU: AMD Athlon 2800+ 2.08GHz RAM: 1GB OS: Windows XP Home Edition Service Pack 3 32bit

Comments by a forum moderator.
(Modified April 30, 2014 12:11:58 PM BST by John99 ) ~J99
Rather a long thread so I will add some comments here where easily seen.

 Modified June 18, 2014 6:08:41 AM PDT by John99

Modified by John99

All Replies (20)

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Oh wow, its way faster now. Worked like a charm. Thanks.

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Perhaps I spoke too soon. It was much faster immediately after applying the fix you suggested, but has since reverted back to the unbearably slow speed it was running at before.

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BrokenEye – if you are using McAfee SiteAdvisor then please read my earlier post.

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I am not using McAfee SiteAdvisor.

A little update, after further review, the problem hasn't actually "returned" as such, but rather seems to come at go seemingly at random, with no correlation with the number of windows open or the complexity of websites contained therein. Its fine again right now, but an hour ago it was a nightmare.

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@pashadad are you the same pashadad who reported DivTag Templates on the WeeblyForums website?

If so can you please add your story to Ripped Off Reports? You can add your own report as well as add your comments to this one and then to mine (link to mine is in here) Thanks!

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@mornaj - yep it's me, another divtag templates scam victim. I'll be happy to add my report! FYI there is also a new one at Ripoff R. with the keywords: "DivTag Templates Scam, Rip-Off, Lied, Cheated Internet" add yours there too! Thanks!

Modified by pashadad

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Someone mentioned back earlier that you don't need "direct2d", either. What is "direct2d"? I just want to make sure before I delete it out of ""

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Seems that the whole line of questioning here assumes that the problem stems from the user's computer and not the FF 27 upgrade.

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Hi seeclear, what issues are you're experiencing and when did they start?

If Firefox tests out well during the beta phase, and we cannot replicate the problem on forum volunteers' systems, there may be a compatibility problem. That is why we ask a lot of questions about the environment and try to rule out some known culprits, such as the drivers for some graphics cards. If a specific incompatibility is identified, often Firefox can be fixed going forward, but usually a workaround is required in the meantime.

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I run on a 2012 MacBook Air, 4GB RAM, OSX 10.8.5

No changes in the environment since upgrading to FF 27.

What's incompatible about that?

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Hi seeclear, it's hard to guess from your description why Firefox 27 is running poorly on your system when Firefox 26 ran well, assuming that is the situation. All I can offer in response is to review the earlier posts in the thread for suggestions to help isolate the issue. If this thread is too Windows-centric, you can always start a new question using the link at the top of the page.

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You're new here, aren't you, seeclear? Firefox never admits that it's their browser. NEVER. It's always your operating system, you computer. There is no accountability. I've already admitted I have a fairly old operating system and computer, yet IE works pretty well for me. I stay with Firefox out of stupid loyalty and aesthetics. I WANT it so badly to work because of this.

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I successfully applied the fix suggested in this thread. This fix was also good for version 27.0.1.

However, upgraded to version 28 last night (with the same Firefox config settings) and Firefox CPU usage hit 99% and stayed there. The browser was totally unusable.

Therefore, went back to version 27.0.1 (I had kept a backup of the files), and Firefox was fast again.

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Hi billm4

It may help if you start your own thread by asking your own question.

From what you say you appear to have found and fixed one problem and that is potentially very useful information to share with others.

Additionally it appears you could be having problems with Firefox 28 but not Firefox 27 and if you were willing to try with both versions installed it could make an interesting comparison. You may hold vital clues to the problem that would be worth filing a bug for and asking engineers to look into it.

Of course if the totally unstable browser is one that has many addons in use that may go some way to explain the problem and make it very difficult to determine the cause of the problem.

If you do start a new question yourself please post back here so that others may follow your progress.

May I suggest you use this link for to start a new question, it is quick as it cuts out a couple of steps, and it is easily recognised by contributors as relating to this thread

  1. special link - XP
    (others not using XP special link (NOT xp))
  2. Please; when using the link; try to follow the prompts you will see to include full troubleshooting information (Use the button to automate the process)
  3. Please also list all security related and any adblocking or scriptblocking software that is in use.
  4. Say whether your Operating System is Windows XP or something else
  5. Post back into this thread to confirm you have started a new question.


(initial edit Modified April 15, 2014 9:14:50 PM BST by John99  )

Sorry if you have a problem.
Please scroll through and read this thread trying any advice offered or linked from the thread. If that fails to help you then please start your own thread by asking your own question.

If you have found a solution
You may certainly post that in this thread, but it may in fact be better still to post a solution in a new thread because that would help us to investigate the reason for the problem and offer the correct advice to others or even investigate and fix the cause of the problem.

Long threads like this get very difficult to follow and tend to include separate problems with similar symptom rather than single problems with single solutions.

Update (30th April) there is a bug but no one seems to be voting on it
If after reading this thread you consider you are affected by the known bug you may consider voting on it. The bug does not seems to be receiving attention and will be rated as a low priority. It seems odd if some of the almost 15k viewers of this thread may think the bug affects them that the bug so far has only three votes. If the bug is known to be affecting many tens of thousands of XP users it may be given a higher priority.


You have been following this from the start and answering questions. Should you consider it helpful, if you wish to summarise the position and advice in a single post I will link that post from the OP question.

This thread is currently highly viewed but rather long

53 replies,     356 have this problem,     6734 views 

'update on 15th April numbers increased to

67 replies,   446 have this problem,      11859 views

2nd Update on 18th June numbers still increasing now 73 replies, 572 have this problem, 25687 views

There is probably no prospect of the thread ever being marked as solved. We may as well leave it open but make useful information easier to locate. For those with known problems and solutions we can cross link to other threads.

Modified by John99

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Hi john99,

I didn't suggest the fix for this problem – the credit for that should go to jigebren: see his post dated 2/16/14 5:15 PM. I simply reported that jigebren's suggested fix for versions 27.0 and 27.0.1 does not appear to work for version 28.0.

Edit Hope you do not mind me adding this link (the post I - in the UK timezone - see as posted 2/17/14 1:15 AM ) /questions/985969#answer-534869 J99

Modified by John99

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I have had the same experience. Jigebren's fix works for v.27, but does not appear to work in v.28.

XP 32bit SP3. 2GB RAM. 2Ghz.

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As stated elsewhere in this thread, like that of petef, mine is an 'older' Windows system (XP 32-bit SP3, 1GB RAM, 3Ghz) and utilises hardware (graphics card, and so on) of corresponding vintage.

At work I am running a modern Windows 7 box and have had no such 'slow response/high CPU' issues with Firefox (up to and including version 28.0).

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To summarize this thread: It's about Firefox 27 (and later) excessive CPU Kernel mode usage when dealing with animations.

The workaround I posted for v27 which is about disabling cairo in can be found here: answer-534869

jscher2000's suggestion about disabling Azure using works just the same: answer-536548

These workarounds are already known not to work as of v28 since was apparently removed in Firefox 28, as cor-el let us know: answer-536622

A more complete description as well as a tight regression window can be found in this bug report: bug 973149

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Until the current issues are resolved with v.28, or somebody comes up with a clever fix, I need to downgrade to v.27 at least so I can use Jigebren's fix.

I have looked at the link , but this lists many unexplained files, and I have no idea what to download in order to downgrade from v.28 to v.27. Can anyone shed any light? Thanks

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Hi petef,

Please refer to my earlier post about downgrading and keeping your settings in this thread – the method worked well for me.

What I tend to do now (live and learn) is take a backup copy of my latest *working* Firefox folder (which is version 27.0.1 at the moment), which makes it much easier to downgrade later if need be.

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