I want to clarify this section a bit. This sentence only applies if you try to use LiveView for client-only interactions, but the docs are very clear that you should not use LiveView for that.
I am aware that you know this, I am commenting to avoid confusion in other threads. 
Assuming you have to hit the server, for example to talk to a database, LiveView response time is actually better than regular HTTP requests because it works over an existing authenticated web socket connection. So the work of parsing headers, authenticate users, etc is not done on every server interaction. Hologram and LiveView should be similar here, as both are WebSockets based.
Similarly, Fly.io gets you closer to your users, which means any server-based application could benefit from Fly.io.
In other words, LiveView is for server based interactions and it excels at that, with or without Fly.io. Indeed, for more complex cases on the client, then you need custom JS (or something that aims to fully cover both server and client, like Hologram).
