[CentOS] which firefox tab is eating my CPU?

According to top, plugin-containe is eating more than 120%  of my CPU?
I expect that that is allowed because I have a dual core CPU.
Firefox is sloooooooowwwww.
I expect that plugin-containe... is running in a firefox tab.
How do I non-destructively discover which one?

I'm running CentOS 6 and firefox 24.8.0 .
I haven't updated firefox in a while because I've read
that doing so will cause me to lose all my tabs.
I'd like to keep them for a while.
There is rather a lot of them

Is there a way to tell firefox not to run a
plugin unless its tab is currently selected?

-- 
Michael   hennebry at web.cs.ndsu.NoDak.edu
"SCSI is NOT magic. There are *fundamental technical
reasons* why it is necessary to sacrifice a young
goat to your SCSI chain now and then."   --   John Woods