Bug#643903: Same Problem

[J.P. Lien]

Just wanted to chime in with the same problem.  Iceweasel is generally
quite slow, and loading ant page with flash makes it unusable, causing
xorg to peg a cpu core at 100%.  When this happens switching between
tabs/windows becomes incredibly slow.

A combination of the workarounds above worked for me.  I put Alexandre's
snapshot line into my sources.list, changing sid to wheezy.  I rolled
back to the snapshot versions of xserver-common, xserver-xorg-core.

At this point I found keyboard and mouse were unresponsive, and so I
rebooted to single-user and installed snapshot versions of
xserver-xorg-input-kbd, xserver-xorg-input-mouse, and
xserver-xorg-input-evdev.

I also rolled back to version 280.13-1 of the nvidia drivers, although
I'm not sure if that was necessary.

J.P. Lien