Mobile phones have less powerful CPUs. Parsing large json objects and then building up a corresponding html structure may be more difficult than on the server (where you already have it loaded into memory anyway).
True - but not by much
> Parsing large json objects and then building up a corresponding html structure may be more difficult than on the server
I doubt it. And you'd only be doing "large JSON objects" for a desktop web app, where CPU differences vs web servers are even smaller
> where you already have it loaded into memory anyway
Likely not true if implementation uses streaming semantics
False. https://infrequently.org/2022/12/performance-baseline-2023/
Or do people study this while thinking about IoT which may use more limited resources while still relying on the internet?
Especially since a server has to handle multiple request concurrently, it doesn't seem to be remotely the same workload that a single device CPU would see anyway?
I will allow that it is probably theoretically possible to do client-side rendering in a CPU-efficient way, but it sure isn't the standard.