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Firefox Mac Very Slow

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This has been happening from the past few iterations of Firefox (I'm on FF 18 at the moment, and I can recall it happening since at least Firefox 15.

Firefox is a HUGE HUGE resource hog. I have permanently switched to Chrome but still use Firefox for some private browsing (no, not for that, it's so I can log in to Tumblr / Gmail on alternate accounts and not have settings saved which annoys me)

Firefox has caused actual physical damage to my laptop - it continually thrashes my CPU on the easiest tasks such as switching tabs or scrolling past a GIF image on Tumblr. My CPU usage skyrockets to 99% and I've even seen it go to 127% which I didn't even think was possible.


The thing is, I have Chrome open with the following tabs:

Hotmail, Facebook, Tumblr, Forums, 9GAG.

And FF open with:

Gmail, Tumblr.

If I load two identical pages on Tumblr, particularly if there is a video embedded, Firefox will bring my macbook to its knees, making switching windows a laborious process. Opening a new tab causes CPU hitching, so much so to the point where I can type a full address into the address bar, take both my hands off the keyboard and raise them up in the air before Firefox catches up and puts what I typed into the bar. Using CMD+1/2/3/4 etc to switch tabs takes about 3 seconds, on Chrome it is instant.


I have no addons installed on Firefox, no theme. Just adblock plus. No other extensions or plugins. Just stock FF and ABP. I have tried reinstalling and resetting Firefox to no avail. This is a problem with your browser that many others have reported.

I'm not the kind of douchebag who expects reimbursement but I'm pissed off that because of the thrashing of my CPU directly caused by FF, the following negative effects have taken place on my Laptop:

High temperatures in the 90c+ rating -

- Causes the fan to spin much faster than it should, which:

• Causes the bearings to wear out, • Makes the fan a lot louder than it should be over time, • Decreases the life of the fan.

• Decreasing the life of the CPU • Has caused the glue on the feet to soften, the rear feet have now fallen off. If you think it is a coincidence, let me remind you that the CPU is at the rear of the laptop. • Lack of feet on rear of laptop have caused numerous scratches and scrapes.


The point is, Firefox, a browser, with two tabs open, one of them being a rarely-active email tab, is throttling my CPU to the extent that Final Cut Pro rendering would throttle my CPU.


I have had enough and decided to see if opera can fit my browsing needs. For the first time in a long time, I have closed down Firefox and, hey presto, my laptop fans have died down and the temperature of the CPU has receded to a normal 60c.


Fact of the matter is, Chrome is just an all round better browser. The only thing I miss from Firefox is using three fingers on the track pad to get to the top and bottom of pages quickly. Other than that I haven't looked back and have been enjoying a fast, smooth, heat and noise free browsing experience.


Nevertheless I would like to continue to use Firefox for my Private Browsing needs, unfortunately I will not be doing so until Mozilla takes a long, hard look at performance improvements to this most sluggish of browsers.



Macbook Pro Mid 2010 model

Mac OSX 10.6.7

Firefox 18 (and now that I've closed it, it'll be Firefox 19)

4GB RAM, 2.26GHz Dual Core CPU

This has been happening from the past few iterations of Firefox (I'm on FF 18 at the moment, and I can recall it happening since at least Firefox 15. Firefox is a HUGE HUGE resource hog. I have permanently switched to Chrome but still use Firefox for some private browsing (no, not for that, it's so I can log in to Tumblr / Gmail on alternate accounts and not have settings saved which annoys me) Firefox has caused actual physical damage to my laptop - it continually thrashes my CPU on the easiest tasks such as switching tabs or scrolling past a GIF image on Tumblr. My CPU usage skyrockets to 99% and I've even seen it go to 127% which I didn't even think was possible. The thing is, I have Chrome open with the following tabs: Hotmail, Facebook, Tumblr, Forums, 9GAG. And FF open with: Gmail, Tumblr. If I load two identical pages on Tumblr, particularly if there is a video embedded, Firefox will bring my macbook to its knees, making switching windows a laborious process. Opening a new tab causes CPU hitching, so much so to the point where I can type a full address into the address bar, take both my hands off the keyboard and raise them up in the air before Firefox catches up and puts what I typed into the bar. Using CMD+1/2/3/4 etc to switch tabs takes about 3 seconds, on Chrome it is instant. I have no addons installed on Firefox, no theme. Just adblock plus. No other extensions or plugins. Just stock FF and ABP. I have tried reinstalling and resetting Firefox to no avail. This is a problem with your browser that many others have reported. I'm not the kind of douchebag who expects reimbursement but I'm pissed off that because of the thrashing of my CPU directly caused by FF, the following negative effects have taken place on my Laptop: High temperatures in the 90c+ rating - - Causes the fan to spin much faster than it should, which: • Causes the bearings to wear out, • Makes the fan a lot louder than it should be over time, • Decreases the life of the fan. • Decreasing the life of the CPU • Has caused the glue on the feet to soften, the rear feet have now fallen off. If you think it is a coincidence, let me remind you that the CPU is at the rear of the laptop. • Lack of feet on rear of laptop have caused numerous scratches and scrapes. The point is, Firefox, a browser, with two tabs open, one of them being a rarely-active email tab, is throttling my CPU to the extent that Final Cut Pro rendering would throttle my CPU. I have had enough and decided to see if opera can fit my browsing needs. For the first time in a long time, I have closed down Firefox and, hey presto, my laptop fans have died down and the temperature of the CPU has receded to a normal 60c. Fact of the matter is, Chrome is just an all round better browser. The only thing I miss from Firefox is using three fingers on the track pad to get to the top and bottom of pages quickly. Other than that I haven't looked back and have been enjoying a fast, smooth, heat and noise free browsing experience. Nevertheless I would like to continue to use Firefox for my Private Browsing needs, unfortunately I will not be doing so until Mozilla takes a long, hard look at performance improvements to this most sluggish of browsers. Macbook Pro Mid 2010 model Mac OSX 10.6.7 Firefox 18 (and now that I've closed it, it'll be Firefox 19) 4GB RAM, 2.26GHz Dual Core CPU

All Replies (6)

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Please update your Mac to 10.6.8, then Reset Firefox Refresh Firefox - reset add-ons and settings

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Whoops, it already is 10.6.8. Bad habit of writing 10.6.7

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Please read again, I said I already reset firefox. I've done it numerous times.

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Nobody has a solution to this problem? Other than the cookie-cutter "have you tried turning it off an on again" is a Mozilla developer going to come out the shadows and go "yes, we realise there has been significant performance degradation with every iteration of Firefox. We'll fix it.

My point still stands. When Firefox is running and idle, it makes my fans continually spin as the CPU is working on Firefox, even though it's doing nothing "and the websites are doing nothing either"

I can have 10 times as many tabs open on Chrome and it doesn't sweat. As soon as I click on Firefox and try to use it my laptop becomes incredibly unresponsive.

Firefox obviously has memory leaks all over the place and I'd like to prove it if I could, are there any programs that log your CPU and Memory history and then show you the graphs at the end?

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A reset still carries over data from the previous profile.
So try to create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

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

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I had the same problem and Googled it, and found your post and many others of the same style. I have found the solution. It was so easy. Go to Tools-Add-Ons to open the 'Add-Ons Manager' and remove any of your old extensions first. I removed five that were outdated.

Then go to Plugins and Disable all and everything here. You will be surprised how fast Firefox is after that. In addition, my Flash Player had to be updated.

When I see that I cannot view something and get a message that I need a plugin, I can enable that which I need. Also, I have a Macbook Pro just like you but it's 5 years old now and it has considerably slowed down since then. I can almost no more use iPhoto with my big photos from the Canon 5D. So part of this problem may also be your computer. Last not least, when you use Youtube often you don't want to miss Firefox because videos load so much faster than on Safari.

Modified by PierreFWalter