Hi HaleBopp, please see the next article because there are a lot of fixes for this issue : [https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix Firefox uses too many CPU resources - How to fix] also you have in your [http://kb.mozillazine.org/Profile_folder_-_Firefox#Windows profile folder] a [http://kb.mozillazine.org/User.js_file User.js file]. '''The user.js file does not exist by default'''. If you create the file, forget it, if you have not create the file then '''delete''' the User.js file, to see if the problem goes away (some programs create and write in the file also). thank you