Problem with 1080i Sky HD Channels

Hi everybody,

at first I have to apologize for my bad english, so please be kind... :cheer:
I got a problem with german Sky HD channels(1080i)
I use the newest OE-PVR for ion with the xvdr-addon
Board is ASUS AT5IONT-I connected via Gigabit-Lan to my VDR-Server (1.7.27 with vdr-plugin.xvdr 0.9.5)
Tuner is a Technotrend 1600 PCI Card

So here´s the problem:

after a short while of playback the picture starts stuttering an lagging...720p channels like ARD ord ZDF are working fine...
Is there any solution how I can solve this? Do I need stronger Hardware? Is there something I forgot to configure?
Please let me know if you need any logs or configs.
Any help would be apreciated.

Kind regards

Liquidolze