Firefox is incredibly slow in Lion. Even a simple click on a tab can take a second or so to switch. And it beachballs all the time, too. I love FF, but this is too much!

See https://support.mozilla.com/en-US/que.../676180#answer-22243

I run very few or no extensions with the exception of Java and Flash. I never, NEVER use stupid toolbars. The problem with FireFox on OS X Lion seems to be related to the OS. The speed of my Internet connection never changed and it continues to be fast for all of my computers, both Mac and Windoze 7.

If you change your default DNS on the Mac to something like the IP address of the Google DNS servers, FireFox and Chrome will run at normal speeds. If anyone needs help with this, please post another message and I will post instructions.

Please post instructions! I have two MacBooks (one running Snow Leopard and one running Lion) and the Snow Leopard one is fine, while the Lion one struggles to even open my home page.

I have the same problem, FF and Chrome are really slow to begin downloading the page, FF and Chrome are at full speed when I go into bootcamp.

It might have something to do with IPV6, this worked for me: http://markandkelley.com/mark/2011/09/fixed-firefox-6-and-slow-browsing-on-lion/

dmmd: Thank you so much! Incredible, like night and day! I upgraded to Lion just 2 days ago. Since my iMac is late 2007, I got a Snow Leopard disc to start with. Running 4GB of Ram, so should be no problem. Snow Leopard was fine, but Lion was like quicksand. Your post was one of the best fixes I've ever run into. Again, thanks!

I've been using Firefox for ages without problems until upgrading to OSX 10.7 Lion. Since the upgrade however, start-up times were taking forever, the internal drive was ticking away furiously and a look at the disk usage in the Activity Monitor application confirmed a crazily high volume of data being written to and from the drive. Close to giving up on Firefox I followed the advice posted here by dmmd123. It took less than a minute to carry out the instructions, nothing scary or difficult, Firefox start-up is now totally transformed and takes just a few seconds. The simplest fix for the most dramatic improvement I've encountered in 22 years of using Macs. So impressed was I that found myself quitting and rebooting Firefox a few times just for fun! Thanks so much for the fix, I don't understand what it did but it just worked. Highly recommended for anyone experiencing this problem.

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First of all, who do you think you are to talk to anyone like you did in your reply? Let me make this short. You are very late and unjustifiably, unnecessarily insulting. If you are having a bad day, take a pill and get off this site. None of us need people like you.

This problem is well known to an awful lot of good people, and far more experienced than you. Just to set the record straight, few people, if anyone, are blaming Firefox. We were trying to identify the problem and find a solution because we like the product so much. You don't deserve to know what the problem was (did you read that correctly? ...was), and I hope the folks at Mozilla shut down your account for good!

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