I have a core 2 duo 2ghz, and firefox.exe uses about 50% of my cpu when playing
a flash movie. i noticed this mostly on muse.mu while watching a music video.
High usage while listening to audio only also. The firefox people are blaming
adobe. I have installed the latest version of flash.

I am running vista business.

thanks

I've got the same problem (under Linux) & I've had enough of it. CPU
utilization jumps to a MINIMUM of 50% when playing a single flash video and it
stays there even after the video has finished playing. I normally have a few
tabs open in Firefox & with just 2 'dormant' (non-playing) flash videos open in
any of the tabs the utilization fluctuates between 90% and 97% - this is
redicilous! I'm running a P4 2.4GHz with 512MB RAM & no other apps open.

High CPU usage can be demonstrated on Mac or Windows by simply embedding 100
instances of a simple swf on a page. This swf is simply a single frame with a
circle drawn on it, and contains no ActionScript. Loading this page in Firefox
on Windows pegs the CPU usage at about 50%. On Mac OSX in Safari and Fiirefox
the result is similar, although somewhat worse in Safari.

If the swf is more complex, the threshold number of swfs to create this issue
is lower (around 30 instances, for example).

This seems to be an issue with FP9. We have not seen this with FP8 and lower.