The basic premise of Next is good, but it definitely has more overhead that in should, has odd "middleware", and is very hard to optimize. I view this mostly as a React problem though since any page requires full hydration and ships everything to the client. RSCs are... not my favorite for sure.

I too have been very frustrated by this, and I made an "Astro for dynamic sites" TypeScript framework called Hyperspan ( https://www.hyperspan.dev ) that aims to fill the gap in the JS ecosystem for a modern fully dynamic option that, similar to Astro, makes dynamic islands easy. I have enjoyed using it in all my own projects. Check it out if you want.

RSC by design does not ship everything to the client. That's one of its basic premises. It ships markup, composed in client interactivity, but you can shed a lot of the code required curate that markup.