Why Does Activity Monitor Say Firefox is 100% CPU?

[Fazzl]

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

 

[Bunker]

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.

 

[Mackilroy]

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.

Eh, Firefox 5 is also CPU-intensive. Ever since FF3 it's gone downhill in CPU usage.

 

[Benbikeman]

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).