[simulate-me]

Why not do something like:

1) Fetch the list of comments

2) Add a listener on the public user info for each comment poster

3) Render the comments immediately. When the user info is available, re-render with the avatar information.

The nice thing about this is that the avatar information will immediately update in real-time as soon as someone updates their avatar. Yes, with a KV-store, you need to do more reads because you can't join data (which implicitly will do a read btw), but it doesn't seem like that big of a deal to me. Immediately reflecting changes to the public user state seems nicer than the convenience of a join.