Earlier quoted context omitted.
It often is that way, but it's not for technical reasons. They're just poorly written. A lot of apps are written by inexperienced teams under time pressure and that's what you're seeing. Such teams are unlikely to choose plain server-side rendering because it's not the trendy thing to do. But SPAs absolutely can be done well. For simple apps (HN is a good example) you won't get too much benefit, but for more highly i…
Yep. In SPAs with good architecture, you only need to load the page once, which is obviously weighed down by the libraries, but largely is as heavy or light as you make it. Everything else should be super minimal API calls. It's especially useful in data-focused apps that require a lot of small interactions. Imagine implementing something like spreadsheet functionality using forms and requests and no JavaScript, as o…
One thing which surprised me at a recent job was that even what I consider to be a large bundle size (2MB) didn't have much of an effect on page load time. I was going to look into bundle splitting (because that included things like a charting library that was only used in a small subsection of the app). But in the end I didn't bother because I got page loads fast (~600ms) without it.
What did make a huge different was cutting down the number of HTTP requests that the app made on load (and making sure that they weren't serialised). Our app was originally going auth by communicating with Firebase Auth directly from the client, and that was terrible for performance because that request was quite slow (most of second!) and blocked everything else. I created an all-in-one auth endpoint that would check the user's auth and send back initial user and app configuration data in one ~50ms request and suddenly the app was fast.