[scrollaway]

[Edit: I don't want to get into this argument right now]

[recursivedoubts]

the original web architecture has sophisticated client-side caching built into it, all modern browsers support it:

https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching

the difference between constructing a string of JSON and a string of HTML is a round off error when compared with network connection costs and data store accesses, etc.

[GordonS]

I'm guessing you haven't measured it, as IME it certainly is true. Try it, you might be surprised.

Also, SSR'd pages can be cached too.