The judder on my MythTV frontend has been driving me crazy for a while now. There was a very simple fix for this: RTFM.
The MythTV team have put together an entire manual on avoiding judder.
It turned out that my judder problem was due to a few problems:
My Nvidia settings was set to enable PowerMiser. This tells the video card to back off whenever it thinks it’s not under enough load.
I was missing the following line in my Xorg conf:
Option "FlatPanelProperties" "Scaling = Native"
I didn’t have proper playback settings in the following menu:
Setup -> Setup -> Appearance Go to the “Video Mode Settings”
I set everything to 1080p and auto.
I don’t know which setting fixed the problem, but it’s nice and smooth now!