My imovies take forever to load. I have ATV 4K. And a good internet speed. When I first got my new ATV 4 k the movies loaded fast. Now it’s simply unacceptable.

Hello JW1111.

Thanks for reaching out to Apple Support Communities. We understand that movies are taking a long time to load for your Apple TV 4K. We will be glad to assist.

Please see the following resource for some troubleshooting steps that can help: If you can't stream or watch movies or TV shows from the Apple TV app, iTunes Store, or third-party apps

Cheers.

Loading iMovie content would have nothing to do with internet as it over the local network. Network issues can come at any time and that is what will require troubleshooting.

You can see a current status of the network from istumbler or similar. This will show values for signal strength and noise along with nearby networks

If on wifi you can try ethernet