I have reported a bug with the same title to nVidia a little over a month ago, but no returns.
No success finding a workaround too, then I'm trying this forum.
This is my nVidia report, with the files from nVidia bug report script:
Informations about the bug:
$ lspci | grep nVidia
04:00.0 VGA compatible controller: nVidia Corporation G86 [GeForce 8400 GS] (rev a1)
$ uname -a
Linux debian 3.1.0-1-amd64 #1 SMP Mon Nov 14 08:02:25 UTC 2011 x86_64 GNU/Linux
Problem: The animations runs like skipping some frames.
Driver version: 290.10-1 (Installed from Debian repositories, already tryed other driver versions and from nVidia website, but do not solve the problem).
I hope finally solve this in some way by this thread.