Disclaimer: I know this question has been asked a ton of times here and other subreddits. I’d still like to add some sources and expand this discussion further.

I watched Theo’s video about RSC and performance benchmarks as they relate to load times. It was based on this great article by Nadia Makarevich.

My takeaway was that, in the best-case scenario, if everything is done optimally, data is fetched in server components and boundaries are set with Suspense, then App Router and RSC deliver proven performance gains.

The article, however, focused mostly on initial load times, and while it mentioned SPA’s key benefit of instant navigation between routes, especially when data is cached, it did not compare it or otherwise account for it.

Now, most apps are more or less interactive, data is often user-specific, and navigation between routes is typically frequent. When you navigate to a previous page, it’s better to show stale data and refetch in the background than to show loading indicators for some components or the entire page.

In some cases, if the user-specific client data doesn’t change often and especially if the network is slow, it doesn’t make sense to always make a redundant network call to fetch the route we have already been to.

And before you say it, yes, I know there is Client Side Router Cache, but aside from prefetching, that works only on back/next navigations (by default, given the staleTimes: 0). And yes, loading pages are cached. And yes, prefetching does help. And you can add user-specific cache tags to cache server components even with user-specific data.

Yet all that said, the things I mentioned above merely bring App Router closer to what SPAs offer in terms of performance, rather than exceeding it. Once the client-side JS is loaded, subsequent navigations are infinitely more important than initial load times, and I don’t see how RSC helps in that regard at all.

I’d love to hear your take on this and see if you can tell any blind spots in my thought process. For now, I just keep bouncing between App Router and basic React apps with Vite. It’s also tiring to keep hearing a strong industry push towards RSC without any objective discussion of whether it’s just a small optimization in the initial load phase, which is mostly resolved by SSR anyway.