gecko browsers: cpu usage on idle

[barbara.xxx1975]

# $FreeBSD: ports/www/seamonkey/Makefile,v 1.254 2006/10/14 08:53:36 marcus Exp $

Hello.
I have a long standing problem, resulting in high cpu usage with seamonkey. The same apply to mozilla and firefox.
Currently I'm running it on gnome2 2.16.1 but I've noticed it for the first time on July 2006.
At that time I was using 2.14, installed on the first day it was available on ports, on FreeBSD 6.1.
Anyway I can't say this was introduced on 2.14 day zero (I'd say no, but I'm really not sure).
This is not present on versions shipped with gnome 2.12.

This is how I can reproduce it on seamonkey or mozilla (for firefox you have to adjust the keyboard shortcuts or use the mouse)
1) open top on a terminal and seamonkey
2) go to http://art.gnome.org/backgrounds/gnome/
3) open in a new tab every image linking a "background"
4) go to the the first of the new opened tab
5) open in a new tab on every link on the gray box reporting "Avaliable Resolution", then close the tab
6) repeat step 5 until all the tabs with link are closed and you reach the first one with a background image

The previous steps are needed to have a number of images within subsequent tabs.
So now you should have the first tab with the home page followed by a number of tabs with images.
The next 3 steps should be done and repeated *fast* until all the tabs are closed but the first.
7) on the first tab containing an image press ctrl+s to open the save dialog (choose a directory only the 1st time)
8) press alt+s to save the image
9) press ctrl+w to close the tab

Check top. the cpu usage is high, even if you keep open only one window without tabs and point it to about:blank

On 2.16, *very* rarely, it also crashes with this message, but I don't know if it's related to the same problem.
-- Gtk-ERROR **: file gtkfilechooserdefault.c: line 7772 (gtk_file_chooser_default_should_respond): assertion failed: (path != NULL)
-- aborting...
-- Abort trap (core dumped)

Feel free to ask whatever test could help!

Cheers

P.S.
As it seems that there are some "reopening" post, I had to say that I also had the infamous "100% cpu nautilus usage" on 2.14.
I use nautilus rarely so I'm not sure it's gone away.
I don't know if it's useful but when it was happening, on ktrace I saw a *lot* of gettimeofday, as someone else said in a nautilus thread.
The same on seamonkey, with a very vary rapid growing ktace output.
Maybe the problem is in a common underlying component?

uname -v
FreeBSD 6.2-PRERELEASE #0: Mon Oct 23 06:18:57 CEST 2006     root at satanasso.local.domain:/usr/obj/usr/src/sys/SATANASSO