The problem is the new update 10.1 of Adobe Flash Player, NOT Firefox.

So . . . what do we do about it? This was happening to me before I downloaded the latest version of Flash Player.

I see this problem too. It's really eating up my CPU.

I switched to Chrome. Chrome and even IE run the new Flash fine, which tells me it is not a Flash problem; it's a Firefox problem. Sorry Mozilla; until this is resolved I'm a Google person.

Version 3.6.6 did not Help at all! It just made things much worse!!! Until they fix this problem, Firefox is now utterly useless to me. The Plug-in container was just a bad idea for the get go. I wish I could just go back to an older version from back before this Plug-in Container was added in. If I had known that this supposed upgrade was in reality a downgrade, I would never have installed it.

since 3.6.5 my firefox is not the old one. it causes many little freeze periods to windows and when it returns then switches back to vista basic design (just itself not the whole windows). (under vista, with the latest flash)

HUUGE issues even when content is not flash but HTML5. The plugin container is eating CPU like crazy

After the update a few days a go this crap is destroying my CPU usuage! To the point that it actually overheats then instantly shuts down my computer. I've never had that problem with anything before. Even running Bad Company 2 on high settings with a ton of firefox windows in the back.

I wish I could downgrade back to where I was, or I guess I'll be using chrome again for awhile :/

Riddiculous update really annoying the f*** out of me now having to restart all the time and it still not working. Ditch the plugin crap or I'll go and use another browser.

Im throwing ff to trash. Will jumt to chrome. bye bye ...

I too am going to have to change browsers. It uses so much mem and cpu that the machine barely runs.

Just annoying...

strange my Firefox 3.6.6 is faster loading, "very fast" and my Old Flash on my home page works faster, loads the web pages way faster.. BUT then I use zonealarms firewall / virus and it keeps asking me permission to run the Plugin container I have said yes few times no issues, when I say NO I have no issues.. but I'm on Vista SP2  Home Premium.

I just watched the CPU and Mem system with firefox 3.6.6 with and without the plugin container running and its the same very little CPU use my PC is running at 5% ... with or without it running.. the ONLY ISSUE I have is whenever there is an other APP running as in this one makes me wonder how long someone will take to make a Trojon, virus or such to embedded "take over" and have access to my full Firefox actions :( ....

You can set the prefs dom.ipc.plugins.enabled.* to false on the about:config page to disable the plugin-container process to see if that helps. dom.ipc.plugins.enabled (currently false by default) dom.ipc.plugins.enabled.npswf32.dll (Flash) dom.ipc.plugins.enabled.npctrl.dll (Silverlight) dom.ipc.plugins.enabled.npqtplugin.dll (QuickTime)

See also http://kb.mozillazine.org/Plugin-container_and_out-of-process_plugins

Firefox has become unusable for me. CPU useage by FF goes up to 50%-100% when opening any site with video, than freezes my whole system, and if I disable the plugin container videos won't play atall.

I have tried ALL [yes ALL] the suggested solutions posted on the many other threads about this.

Frankly I don't really want to be installing/uninstalling plugins, FF, rolling back etc etc. It was all working fine and since an update now it is not.

Since FF is now unuseable due to total lockup when opening sites, and since I've actually got better things to do than be reading reams of work arounds on forums or trouble shooting this that and the other I am reluctantly giving up on FF until I read that it has been solved.

I've seen this problem for the past few days, firefox pegs one core for a few minutes at a time and then the subsides. In my case its not the plugin container that is pegged, but the main application.

Looking forward to 3.6.7 and a fix :-)

Cheers Mark Levison

Ever since upgrading to Firefox 3.6.6 with the new Flash Plugin 10.1 on June 24, 2010, I have experienced numerous problems that previously did not exist. First, I too experience significantly increased CPU usage while running apps that use the Flash plugin. Normally I run ScottradeELITE Stock Quotation system, Excel, Quicken, Outlook, and Firefox with about 8 tabs open. My CPU usage ranges between 5% - 15% for these apps. The second I run anything requiring Flash Plugin CPU skyrockets. If I watch a video on YouTube at 720 resolution the CPU shoots all the way up to 75% - 85%. Furthermore, video playback on YouTube is not as smooth as it was prior to the upgrade. It’s now sometimes jerky and the frames seem to jump frequently as if a big section of the video was cut out. Prior to the upgrade video ran smoothly at 720. It’s now almost impossible to watch a YouTube video at 1080 whereas prior to the upgrade I could usually watch at 1080 without any problems. Furthermore, I check the speed of my Cox Cable Internet connection 4 times per day using DSL Reports test site. I should be getting 20 Mbps download speed and that’s what DSL Reports consistently confirmed until I upgraded Firefox on 6/24/2010. Now the results are significantly distorted showing a speed of only 3-6 Mbps. At first I thought it was Cox but they confirmed no problems. Then I tried Google Chrome and I did not experience any of these problems. Video runs fine on Chrome and my Internet speed tests show accurate speeds. Finally, the Flash Plugin 10.1 has crashed 4 times since 6/24/2010. Prior to the Firefox upgrade I had never ever experienced a crash of the flash plugin. I run Windows XP Media Center SP3, Intel Pentium D Dual Core Processor, memory-2GB DDR2-667MHz SDRAM, graphics card-256MB DDR ATI Radeon X1300 Pro. The solution for now is to run Google Chrome since there are no issues or problems as just described. However, I much prefer Firefox so I hope a solution is quickly on the way to users.

Same issue here. Firefox started working extremely slow after an upgrade. Currently on 3.6.6, but the speed is not feasible to work fluently :( Hope they solve the issue fast.

Same here, FF freezes every second time I enter a site with flash contents, especially youtube. Please fix this asap as FF is the only browser I want to use but right now its almost unusable.