■ Beta is experimental The Beta and Firefox 4 is at present experimental and being tested, you would be better off trying the latest version 3 instead. ■ You may well have an old low spec overworked computer using sites with heavy video content. * see this [http://support.mozilla.com/en-US/questions/772823#answer-126218 thread] where someone asked similar questions ■ Also see * [[Firefox hangs]] * [[Basic troubleshooting]]