[starkman]

Looking for a Kodi device for a 1080p tv. Is there a noticeable performance difference between the HD an 4K device?

1080p feels like the logical choice, unless 4K version makes the kodi experience better. They have different chips but unsure what this means in practice. Read somewhere 1080p supports av1.

I've recently got the HD version of CCwGTV and Kodi runs really smoothly. Huge difference in comparison to any X-name Chinese box with Android and double the ram / storage specs (my Mini M8SII box with 2GB RAM / 16GB storage never managed to run Kodi without performance issues, because of non-optimized software / I had to resort to CoreElec to have a decent experience). Just make sure to move the thumbnails folder to an SMB / network drive if you have a big library because the limited free storage of CCwGTV might get easily full. I have also installed the KCleaner add-on and I have no issues with cache / junk files filling up the Chromecast's storage.
Most reviewers say that the 4K version is generally not that much faster - actually they hardly see any performance difference, so I guess that must be the same with Kodi, too.