Why Does Activity Monitor Say Firefox is 100% CPU?

Discussion in 'Mac OS X Lion (10.7)' started by Fazzl, Aug 10, 2011.

  1. Fazzl macrumors 6502a


    Aug 13, 2007
    Don't mind the not responding, it happens sometime with Firefox. But why does it list CPU at 100 or sometimes over 100%?

  2. Bunker macrumors member

    Oct 28, 2007
    Flash. Update your Flash player.

    Also update your Firefox to latest version 5.0.x.

    Best is to move to safari or Chrome when using Lion. :D
  3. Mackilroy macrumors 68040


    Jun 29, 2006
    Eh, Firefox 5 is also CPU-intensive. Ever since FF3 it's gone downhill in CPU usage.
  4. Benbikeman macrumors 6502a


    May 17, 2011
    London, England
    It's definitely Flash player rather than Firefox itself. Visit a series of webpages with no flash at all (NB: most banner ads use Flash) and it's fine. Visit Flash-intensive sites and it goes crazy.

    I've reluctantly switched to Safari for now (which also has Flash issues, but copes better than FF).

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