It's super easy to blow your budget on a higher-spec'd SoC, too.

We made responsive applications on 1980s era 16-bit and 8-bit computers. We did it by being conscious of what we were doing in each cycle.

There's a huge budget to burn on even an older super cheap SoC.

Often what is making the screen lag is accidental stupid pointless idle states (blocking on I/O etc.) inside tight animation loops.

Lag and jank aren't usually a throughput problem, but a latency problem.

Diagnosing and fixing this requires concern and effort and recognition that it's actually super important to the consumer experience.

You get what you pay for.