also this problem was not found in later version of FF

Hello,

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Thank you.

safe mode not solved problem.

can you reproduce in a new profile?

• Profile Manager - Create, remove or switch Firefox profiles

I created new profile. All of my add ones are removed. But problem is still alive

So no addons etc. can you test in safe mode (the windows kind) with networking.

• http://windows.microsoft.com/en-us/windows7/start-your-computer-in-safe-mode

Does firefox use as much CPU in safe mode?

I tested firefox in safe mode(not windows) and the problem is remained. Does anyone see www.tsetmc.com to check CPU usage?

Sorry, but i cant reproduce, my cpu usage is around 5% with that site open, can you disable hardware acceleration.

• Click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
• In the Firefox options window click the Advanced tab, then select "General".
• In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox.
• Now, restart Firefox and see if the problems persist.

Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

I disabled HW acceleration and it solved