[dgb23]

To expand on that, CSR doesn't automagically save you from round-trips. It enables you to be agnostic where your data structure is built, but there are a lot of cases where you need to do that on the server anyway.

Then there is caching, if your stack is well-integrated and aware of mutations you can respond with 304, or you can intercept requests with serviceWorkers, or edge/cloud workers/functions etc. AKA speed of light or practically instant responses.