I have tried different combinations of TV settings and Apple TV settings and have not resolved this issue. I have tried the Apple TV on another TV with the same HDMI cable, same issue. I have tried the Apple TV on another TV with a known good HDMI cable, same issue. I have streamed YouTube videos, same issue.
Not sure what else to try, thinking it's possibly a dud Apple TV. Or the fact that this is all running across a wireless network? But wouldn't expect a wireless network to impact the performance like this.
Any help appreciated.