It sounds like I am not alone...

When loading certain websites Firefox freezes. I have to go to task manager and force Firefox to quit. When it does it says that plug in container stopped working (as opposed to any plug ins). I restart Firefox and it may or may not work. Previous versions of Firefox did not have this problem, and other browsers such as Google Chrome do not have it either.

Same same ... 3.6.6 + Vista. Hangs on youtube and other sites with embedded media ...

On Linux, Firefox starts normally if you delete the contents of .firefox (backup your bookmarks first, just copy the most recent .json in your profile to other folder) in your home folder, but then all passwords, add-ons etc are then gone too.

I've tried disabling add-ons, deleting the current profile, using an older profile but to no use.

Firefox 3.6.4 and 3.6.6 use a process called, "plugin-container.exe" which was using up most of my CPU when I opened up multiple tabs that contained Adobe Flash files, and caused Firefox to lock up.

My solution was to use Firefox 3.5.10 which you can get from the Mozilla website at http://www.mozilla.com/en-US/firefox/all-older.html I am using Adobe Flash 10.1.53.64 without any problem in this version of Firefox. Check the release notes, I believe it contains all the latest security fixes in "Firefox 3.6.4".

Hopefully, they will fix Firefox 3.6 in the next version (e.g. Firefox 3.6.7), until then you should probably use "Firefox 3.5.10".

For me Firefox hangs on startup in safe mode. On some attempts the error says "plugin-container.exe" other attempts "firefox.exe". Only hanging since latest update.

Same problem - I use Process Explorer and kill the plugin-container.exe child app, which frees the rest of the Firefox process, but Flash regularly hangs (and PDFs do also). This is a REAL step backward for us.

FF 3.6.7, Win XP SP3.

I am currently using Firefox 3.6.8 (and i think it did this with the last version loaded / updated also) but for the past two weeks Firefox freezes up after about an hour or so. First all pages begin to load slower and slower, right click boxes start to take 2 then 5 then 10 seconds to show (or never show at all), and then eventually Firefox becomes completely unresponsive. I used to reboot the computer every time but have since found out that I can go to task manager and shut down Firefox then reopen it and it works fine again. I have been reading many posts and have uninstalled Shockwave Flash (Adobe) from their web site and reinstalled it and I still have the problem. I have even disabled the application while browsing and still have the problem. This is completely unstable right now and beginning to waste time as much as IE when it crashed all the time. The only advantage here is you can easily restore your last session tabs. I have also noted that Firefox claims after the update of this it fixed the freeze up problems. Well I am here to say not so with the rest of these postings. If this doesn't get corrected soon, I am thinking I will try Google Chrome to see if that works normally the way Firefox used to work. Please fix this Mozilla as I dread to go back to using IE!

Reinstalling quicktime fixed it for me using vista.

Okay I think I got this fixed, at least on my machine. Hopefully it will work on others also.

Background: Apparently the newest version of Firefox loads certain plug-ins in a separate process to prevent crashing ie if one page goes down the whole system doesn't go down. Problem being created was it absorbed system resources apparently creating the freeze ups. There is a way to go back to the previous method without downgrading your Firefox version. I will post a link shortly below to correct that item and eliminate the freeze ups. Also, while investigating since I last posted, there are numerous ways to speed up Firefox depending on your connections speeds. I have down numerous of these suggestions and my Firefox has sped up dramatically. I closed with 12 tabs open and they loaded in about 5 seconds when I opened Firefox. Speed problems: Disable Quick Time plug in and only enable it when / if you need it. This appeared to be taking enormous amounts of resources after about an hour of usage. Make sure you have the following add-ons - ADBlock Plus, WOT, FastestFox, and Flashblock (with this you will need to whitelist sites that you want Flash to work on e.g. GMail). I usually have 20-40 tabs open at any given time and my computer has not froze since speeding up the system and adding Flashblock while disabling Quick Time plug in. (It did crash once but no more freezing and no more slowing down as browsing continued on tabs.)

The setting that returns the newest version of Firefox to the way it was before can be found here:

http://www.technogadge.com/how-to-stop-firefox-plugin-container-exe-process/

Other links will be provided shortly to speed up Firefox based on your computer. Hope this works for you!

I have also done some Windows Vista optimization strategies and EVEN that has gotten better. Good luck!

Making Firefox faster Helpful sites – (Note some of this can be repetitive, and some dated.)

1. I liked this one although not complete, tells you how to make adjustments based on your computer and connection speeds. http://www.dagorret.net/2010/04/26/optimize-firefox-as-equipment-characteristics-and-speed-adsl/

2. This site gives a good complete overview on what to try and change to pick up speed. http://webanthology.net/all-you-need-to-optimize-firefox-for-better-performance-33-tips/2009/11/29/

3. This site has some screen shots which sometimes helps to visualize when you are doing this stuff. I do disagree with a blank home page though. I like mine to go to a search engine ( I use Google). I’ll accept the one or two seconds and takes to load that page and its’ resources. Blank pages are ugly! http://www.makeuseof.com/tag/the-ultimate-guide-to-speeding-up-firefox-3-5/

That should do it for Firefox, the rest of my links were for Windows Vista optimizing. Again, if you don’t have them, I highly recommend the following add-ons:

Ad Block Plus – Who wants to look at advertisements anyhow? (This is just amazing on how it cleans up browsing!) - https://addons.mozilla.org/en-US/firefox/addon/1865/

WOT – You’ll need this because some of the features to speed up Firefox decrease its security supposedly. - https://addons.mozilla.org/en-US/firefox/addon/3456/

Flashblock – This I just added and am still tweaking. The thing you must do is create a whtelist for sites you want to have run Flash: YouTube, Gmail, etc. - https://addons.mozilla.org/en-US/firefox/addon/433/

FastestFox- I don’t know what all this does, but just the scroll down for the next page feature for most web sites visited is well worth loading it. https://addons.mozilla.org/en-US/firefox/addon/9825/

Tab Mix Plus – I like this one just to be able to customize the tab features. https://addons.mozilla.org/en-US/firefox/addon/1122/

Better Privacy – This can get rid of so called long term or permanent cookies that are not cleared when you clear your cookies history. Marketing companies, adware, spyware, etc. usually put these on your computer. They are called LSO’s here and can be removed. If you don’t have this loaded, you are gonna be amazed or freaked at all the sites that are tracking your key strokes. https://addons.mozilla.org/en-US/firefox/addon/6623/

Same problem with FF3.6.6 and Win7x64 Ultimate. I wish I had seen this post before I rebuilt my entire machine! At least I know what the culprit is now.