Firefox...crashing or freezing all the time? fix it now!

i've heard of a lot of stories about firefox users saying it crashes all the time or freezes and they can not handle it when they're trying to log into some social websites as Facebook per example or games ..
The Solution is simple ...
The first thing is to Determine the responsible Plugin :

• On the menu bar, click on the Tools menu, and then click Add-ons. 
• The Add-ons Manager tab will open. In the Add-ons Manager tab, select the Plugins panel.   
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• Select a plugin in the list and then click its Disable button. 
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• Repeat this step for each plugin in the list. 
• You do not need to restart Firefox for the changes to take effect. 

Test for your problem. If it does not occur, go back to the Add-ons Manager tab and re-enable plugins one-by-one with the Enable button until you find which one causes your problem to occur.

The Second thing is tore-install or update Plugins :
 Check on your Plugins here : Mozilla updates
the Third thing is :

•  In the Location bar, type about:config and press Return. 
• The about:config "This might void your warranty!" warning page may appear. 
• Click I'll be careful, I promise!, to continue to the about:config page. 
• Search for the preference: plugin.expose_full_path. Double-click on the plugin.expose_full_path preference in the list to change the value to true.
•  Enter about:plugins into the Location bar to display the About Plugins page. Each entry in the About Plugins page will have "File name:" followed by a path. 
• Navigate to the folder shown for the plugin you want to remove. Rename the file to something other than its normal name - e.g. npswf32 becomes Xnpswf32 Double-click on the plugin.expose_full_path preference in the list on the about:config page to change the value back to false to avoid exposing the plugin path to websites. 

The plugin will be removed.

The fourth thing is : 
re-initializing Plugins Database :

•  Open your profile folder: On the menu bar, click on the Help menu and select Troubleshooting Information. 
• The Troubleshooting Information tab will open. 
• Under the Application Basics section, click on Show in Finder. 
• A window with your profile folder will open. 
• On the menu bar, click on the Firefox menu and select Quit Firefox. 
• Delete the plugin reg.dat file.
• Open Firefox In the Location bar type about:plugins and press Return to bring up the Firefox plugins list. 

With Medias if you can not Play Games per example :
Use this link here and follow steps !