Noticeably faster on subsequent page loads compared to the first one, sure. But many SPA take longer, in general, to get to the usable point than this netscape page.

Yes that is why I explicitly said "after the first one". That was my whole point it is slower on the first and faster on later ones. Which is why they are for Applications

The performance of website SPAs over time isn't the comparison I made. In my experience, the first, second, and any later load-to-usable time of a SPA is longer than the load-to-usable time for websites that are implemented like this netscape site.