Apple TV 4k (2.gen) Lagging when streaming

Hi, Today my one year old ATV 4k startet lagging when looking at tv, streaming. I tried several different tv-apps, reboot of both router and the apple tv, went from wifi to ethernet (over 100mpbs), changed HDMI cable, and finally a full hard reset. The problem is still there Tried on antoher TV, not better. Have an older Apple TV and it works fine, even as I tested it on the same tv as the 4K was connected to. Anyone experienced the same, and have a solution? (Latest SW downloaded)