[mythtv-users] High xorg CPU utilization on certain OTA channels

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I am running MythTV 0.20 ATRPMS on Fedora Cora 5.

Quick specs:
- P4 3gHz
- 1 GB RAM
- nVidia 6200 AGP video card w/xVMC turned on in MythTV
- pcHDTV 5500 ATSC tuner
- Two kWorld ATSC110 OTA ATSC tuners.

I can watch most of my OTA ATSC channels just fine.  My typical CPU 
usage while watching live TV (according to "top" running in a ssh 
connection to the MythTV box) is 50-60% CPU utilization being used by 
mythfrontend and 5-10% being used by xorg.  So everything is perfectly 
fine.  These utlization levels are while watching HD content.

The odd thing is two channels I use (Fox and ABC in Buffalo NY) cause 
xorg CPU utilization to spike to 50-60% CPU utilization. As a result 
these channels stutter when watching live TV.

If I let Myth record the shows on these two trouble channels I can watch 
them later without a hitch.

I am stumped as to what could cause this.

Any ideas and or suggestion of what to look at?
Anyone else experience this weird xorg spike in CPU utilization while 
watching certain channels?

Thanks in advance.