I was having this issue too, but I'm running on Windows 7 64-bit Professional. I upgraded from Firefox 5 to Firefox 6. Afterwards, even after a Firefox and OS restart, Firefox would freeze for 30 seconds - 1 minute whenever I hit Ctrl+Shift+E (Tab Groups). I have about 11 Tab Groups open, with about 40-50+ tabs in total.

What worked for me is the following:

1. Open each tab group. FF6 loads the Tab Groups only when it's "active" now, instead of trying to load every Tab Group when FF starts (like it did in FF5). Otherwise, it keeps a cached thumbnail of each tab (from my observation). If you have not "activated" the tab group since FF6 was launched, you may be getting a blank/white thumbnail.
2. Completely clear you cache. Click Firefox-->History-->Clear Recent History, or Ctrl+Shift+Del (if you're running the default shortcuts). Clear EVERYTHING.
3. Restart FF6. Hopefully, when you load up Tab Groups now, it should be fairly quick. It still loads each Tab Group only when "activated," but it's not freezing anymore.

Hope this helps!

Its not just the Tabs....everything else has decided to come to a crawl

My Box Dual 3.8 Xeon Processors 16 Gig Ram Windows 7 64 bit.

No antivirus

FireFox setup is Remember No History Running default theme I have maybe 6 plugins all of wich are up to date Network Cache is always cleared

Would someone from support chim in because this has become a major issue.

Thank you very much.

I'm having similar problems - both with Firefox 6 and Thunderbird 6 - I'm using Windows-7 on a generously specified laptop.

I've tried clearing the cache - and while interactive response seemed to improve for a short while, was back to square one once I'd opened a few tabs. Not only opening new tabs, but switching between tabs seems to cause a problem - often taking over a second to switch - where, with FF5/TB5, I could switch as fast as my screen refreshed. Now, I'm counting the seconds even when I just ask it to open a blank tab... so, for me, this isn't a network speed issue.

I've cleared out the obsolete Java Console add-ons, leaving me with:

Adblock Plus 1.3.9 British English Dictionary 1.19.1 Property Bee 2.0.11.0 Xmarks 4.0.1

As far as I can tell, none of these are the cause of the problem... and they're only installed in Firefox - not Thunderbird.

I'd happily down-grade...

Weird observation...

While FF6 under Win-7 is almost unusable, FF6 under Ubuntu running under VirtualBox on the same hardware works fine... with the same add-ins.

This definitely looks like an issue with FF6 on (?64-bit?) Windows.

I have a similar problem.

Firefox 5 was working fine until I upgraded to Firefox 6.0. I am running Windows 7 SP1, 32 Bit on a reasonably powerful Desktop. I have a fast Internet connection, which gives me a real 20 Mbps Download speed and a 2 Mbps Upload speed.

Google is my first Tab, plus 12 more. Before upgrading to FF 6.0, I used to load all tabs in a second or so. Now it takes over a minute to load all thirteen Tabs. However once all tabs are loaded, FF 6.0 appears to be as fast as FF 5 was.

My Java and Flash are both fully up to date, as are all Microsoft Updates. I have cleared my Internet Cache. I am using Microsoft MSE Anti-Virus. I would like to revert to FF 5.0 until this problem is resolved, but cannot find a a FF 5.0 Download on the Mozilla Website.

Any suggestions would be much appreciated.

Been really disappointed with speed of FF6 in W7 since I upgraded about a week ago - images take forever to load, urls just hang, virtually unuseable.

I uninstalled/reinstalled and nothing improved but then I remembered that there is a profile folder called "Mozilla" in C:Users/Username/appdata/roaming. I uninstalled FF again, deleted this folder, and reinstalled FF6 from scratch - now works like a dream. Must be something in the profile folder that doesn't upgrade properly. *(Remember to take a backup of your bookmarks etc. before you uninstall FF and delete profile).

Hope this helps someone out there.....it did for me!

Another thought - it might be just possible to delete the profile folder without uninstalling - FF6 should rebuild it, but would advise caution in doing this.

Not sure if this is related, but ever since I upgraded from Firefox 5 to 6, I'm having intermittent freeze-ups of around 20 seconds, and CPU load goes through the roof. Firefox also starts using over 1 GB of memory after prolonged periods of usage. This didn't happen with Firefox 5.

Thank you 'WhoRu'. I tried your suggestion and this has fixed my problem.

I Backed up all my Bookmarks and then completely uninstalled FF6. When complete, I checked to make sure that all the User Application Data for Mozilla Firefox had also been removed.

I then did a fresh install of FF6 and after setting up FF6, I Restored all the Bookmarks and now everything seems to be O.K..

Try uncheck "tabs on top" in the option. It works for me.

Win7 Pro 64: I uninstalled FF 6.0 completely (went through with registry cleaner and verified no remaining files via Win explorer search, double checked empty cache). Reinstalled without any significant add-ons. Still no dice: dog slow. Its simply unusable for any sustained browsing. For the first time (I've been using Firefox since the early days), I've actually had to switch to Chrome as my default browser, at least until this is resolved.

I have tried all your suggestions (thank you) still takes FOREVER to open.

I have the same problem, only with μtorrent open, but in the same time i upgrade to firefox 6 and to NOD32 version 4.2.71.2 I was worry about firefox slownest and i solve the problem by excluding μtorrent from the web browsers list in NOD32. From then all is ok. thank you.

I've used Firefox forever and it was always fast and beat IE hands down. I've installed and removed Firefox 6 four times with the same poor result. Therefore, I've had to resort to IE 9 which is very fast. I'm an IT tech and have recommended Firefox to hundreds of clients.... I hope they don't install Firefox 6.

I'm in the exact same boat here. Working with Chrome until this issue is solved!

Solution I've toyed with that worked for me: I turned off "Hardware Acceleration When Available" under Firefox --> Options --> Options --> Advanced Tab --> General Tab

I also disabled the following Plugins under Firefox --> Add-ons --> Plugins: Microsoft Office 2010 Plugins (2 and may be Office 2007 etc. for others); Silverlight; Windows Live Photo Gallery

I then right clicked the Firefox icon on the taskbar and unpinned it. Went to "C:\Program Files (x86)\Mozilla Firefox" folder and turned on "run as administrator" by right clicking the application icon and selecting properties --> compatibility tab --> run this program as an administrator check box...apply settings...click OK. Then right click the icon again and pin it back to the task-bar. You'll get an annoying pop-up from Windows about approvals...follow the prompts and disable these warnings.

I didn't clear the cache as I wanted to verify the potential fix with these changes I had performed...but I did restart Firefox...seems MUCH faster now...not sure if either/or of the solutions I provided fixed the issue for me.

I also noticed that the navigation of the Firefox icon within the All Programs link under the Start/Windows Icon in the bottom left changed from the "C:\Users\xxx\AppData\Roaming\Microsoft\Windows\Start Menu\Programs" folder to the actual location of Firefox "C:\Program Files (x86)\Mozilla Firefox" folder...sneaky bastards. Not sure if this was due to a Microsoft update or their sly means of tracking Firefox users...but I'll be sure to keep an eye on it.

Seems to no longer hang when scrolling and loads faster on forums...for now, but the problem seemed to exasperate the longer an instance of Firefox ran before the solution above...I'll update again with thoughts on this being resolved. For now, it seems to be the same Firefox I fell in love with :)

Other Solution to annoying problem regarding the two instances of Firefox in the taskbar after updating from several versions ago:

After you click on Firefox in the taskbar and a new instance appears, right-click on the original instance and select unpin from the taskbar, then right-click on the instance still open (the second instance) and pin to taskbar. Close Firefox and click on the icon in the taskbar and smile at the results :) This may be required after updating Firefox each time...dunno.

I have discovered that since upgrading to 6.0, FF will KILL my computer as long as I have the Flash add-on enabled. CPU runs 80%+ and VM size keeps creeping up towards 1GB until my machine dies. So until they get this fixed, I have to use a different browser if I want to view anything with flash content. BTW - I never did like flash - now I know why Steve Jobs kept it off the Ipad!

Got bad news for you.... Those fuckers at microcrap, Steve balledmer and bill gates (CROOKS!) selling windows 7 GARBAGE.... Don't go to google chrome either! I was using chrome and my computer went to a crawl then I checked task manager and the CPU was at 100% usage it was using 500 megabytes and went to 800 as I was watching it!!! These people HAVE NO IDEA how program computers anymorons!!!! You see, at the bottom is microsoft, so everything above turns to trash too.

It seems I am not alone, but since the software upgraded to 6.01 everything crawls, sites take forever, I also am getting bad gateways (got this while paying for a product, not even sure if I paid or not).

Also getting server errors on sites that never happened before.

Ridiculous, will have to abandon this browser!!!

I am really starting to hate FF but I can't stand the other choices either, tools I use like SEOBOOK are not avaiable on Safari, Chrome is no good for any business type of plugins and IE, is well IE and still bugs me. Firefox fix this, it hangs all the time , I am getting this white screen all the time since I updated to most recent version and I am just so sick of this.