I have the same problem on amd64, iceweasel stop responding and eating 100% cpu for few seconds.
Linux samuel 3.2.0-4-amd64 #1 SMP Debian 3.2.35-2 x86_64 GNU/Linux iceweasel 10.0.12esr-1 -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
