No question it's slower than serving only the changes.

However, it's also dramatically easier to implement. Tracking the precise per-client changes is a huge project and architectural change for most existing systems. It's also easy to get wrong. If you get it wrong, it's difficult to know that it's wrong - the clients just end up with the wrong state.

Serving the entire client view is, in contrast, much closer to how existing application stacks typically work. It's stateless. You can change the schema of your client view at any time and it just works.

And remember that you're not serving the entire client view over the internet to the device. You're serving it to another backend service which calcluates a diff to send to the client.

You can of course use any standard caching techniques on the backend to make it faster to serve the client view.

By default Replicache polls every 60 seconds. This is nice for development because it gets you up and running fast.

For production, we recommend that you set up some kind of push channel and send a "poke" over that channel to tell the client when it might be a good time to sync.

No problem. You can implement the integration points as serverless functions. Our samples are all implemented this way.