I've run a few more tests since I wrote the e'mail and I appears that there is something odd with these encoded southpark episodes.  They peg the CPU at 100% while playback under totem, but barely touch the CPU with mplayer.  However, play back of other files similarly encoded (640x480) avi/xvid/mp3 barely touch the cpu and do not display the stuttering problem with totem.  The only thing I can determine that's actually different is the frame rate.  "file" says the avis i've encoded are 30fps while the SouthPark episode is 23.98 fps (I didn't encode that one, I think it's in PAL format).  I have one high resolution video saved on a dvd around here somewhere, if you think it's necessary I can track that one down and try it as well.  If I can help further, please let me know. --- On Thu, 4/30/09, Sebastien Bacher