> So your initial page load would be slow because of all the HTML and JS, but afterwards it should be faster compared to having server side rendered pages TFA

> So your initial page load would be slow because of all the HTML and JS, but afterwards it should be faster compared to having server side rendered pages TFA is arguing that a user on a bad connection won't even make it to a proper page load event in the first place. It's probably also worth mentioning that the "gains" from sending only data on subsequent user actions are subject to devils in details, namely that response data isn't always fully optimized (e.g. more fields than needed), and HTML gzips exceptionally well due to markup repetitiveness compared to compression rate of just arbitrary data. Generally speaking you can rarely make up in small incremental gzip gains what you spent on downloading a framework upfront plus js parse/run time and DOM repaint times, especially on mobile, compared to the super fast native streaming rendering of pure HTML.