Why still do movie and TV thumbnails have to redownload every time?

I have 1200+ movies. A frustration is that every time I browse my library, thumbnails for the movies have to be download new every time. With so many movies, this takes a long while to sync. I am on a 100+Mb connection, so that is not the problem. Is there in way to cache these images? I don't use the space on my Apple TV for anything other than some streaming apps. I don't play games or anything else on the Apple TV.