Updating the Performance Inequality Gap series [1] (post soon), but here's a teaser: new CPU charts, by price band. Single-core perf matters for web apps, and I won't sugarcoat; it's grim.

The fastest Androids are half as fast as contemporary iPhones (now 4+ years behind) and volume devices (~$300USD) are 1/5th as fast as iPhones.

Building for iPhones erects walls around wealth and precludes effective access to participation in society for those without means.

[1]: https://infrequently.org/series/performance-inequality/

The promise of frontend frameworks was that a local snapshot of the app's data model would be faster to operate on than a server round-trip.

This is a measurable question, and for nearly every class of app, the reality is that you should keep your data on the server and send partials to innerHTML if you want "interactivity".