[acdha]

> other metrics suffer (time to interactive, TTFB and several other metrics are primary examples).

This is only true for a fraction of sites - the ones I work on are content heavy and use progressive enhancement so TTFB is how long it takes a CDN cache hit to transfer, and since you’re using so much less JavaScript in the critical path they’re less affected by network latency and device performance. Obviously that hits a different trade off than an app which has to have dynamic functionality to meaningfully load and lots of user-specific features are going to lower cache effectiveness.

As always, you get what you measure: pick metrics which matter for your business and get as much as possible get your data from real users so you don’t waste time chasing something people don’t care about. It’s too easy to focus on, say, making your search page as fast as you can when you should be asking whether you have what they’re looking for and surfacing it for them.