Firefox throbber problem

["[KS]" <lists04@fastmail.fm>]

Hello all,

I noticed yesterday that when I hover the mouse over the firfox throbber
(the round circle of dots just below the window-close button on
top-right of window), the CPU usage goes to about 100%. It goes back
down to normal after a few seconds. The time duration of the cpu usage
surge looks to be equal to the time the tooltip that should be displayed
 when hovering over it. No tooltip is displayed and the CPU usage rises up.

I thought of posting here first than filing a bug for two reasons.
Firstly, this will confirm that I'm not the only one having the problem
and secondly if its only me, this post will help the (huge) Firefox bug
list to not increment by 1.

Thanks,
/KS

Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20050922
Firefox/1.0.7 (Debian package 1.0.7-1)