Its rough. The AppleTV is so much better than the Roku.
I would really be looking at the client, not the server or the DB. 100% the AppleTV is making requests that no other client is making. Or its making the same requests, just a huge number of them.
I tested this for a MITM between an iOS client and my server:
The problem is that the tvOS method appears to be brain surgery and a bit more work than I want to put in at the moment.
But you could capture every request these clients are making. I guarantee the AppleTV client is doing something no other client is. Understanding what those request(s) are would tell you what needs to be changed in the DB or more likely changed in the AppleTV app.
This isn’t the first time the AppleTV app needed help. A couple of months ago you guys fixed an issue where it was slow as hell and collections would never load.