Resolution for still images that will be displayed on a 4K tv screen

You want the image size of the still images to be at least 3840-by-2160 in RGB color mode (about 8 megapixels and PNG is a good choice) in a 2160p Sequence at whatever frame rate the 4k video screen supports.  The stills should be single layer images.  So if you have multilayer PSDs or TIFs, save flattened duplicates for Premiere Pro.  

If you want to push in or pan them, you'll want the still images to be 1.5 to 2 times 3840-by-2160.

While working in Premiere Pro, do try the following:

• Set the Playback Resolution to 1/4 or 1/8
• Set the Paused Resolution to 1/4
• Set the Sequence Video Previews to QuickTime ProRes 422 LT

Hopefully, you're working from fast storage media (SSD is ideal).

As long as your computer isn't more than six to seven years old and is an i5 Intel/Ryzen5 or better with at least 16GB of RAM, it should handle 2160p stills well.  An i7 or i9, Rysen7 or 9, or M1 or higher should handle it very well.

Hello!
Thanks for the message. Sounds like an interesting project. We'd love to know the resolution of the images in terms of frame size. Are the images overly large compared to the frame size of your Sequence. Are you needing to scale them down? That may be the root cause of the issue. We'd also like to know about your computer and its components: CPU, GPU, and RAM. Can you provide that info? Finally, since your display is 4K, would you like your sequence to be 4K, as well? Let us know that detail too. Sorry for the frustration. Hope we can help with just a bit more info.

Thanks,
Kevin