In practice, you generally see the opposite. The "CPU" is in fact limited by memory throughput. (The exception is intense number crunching or similar compute-heavy code, where thermal and power limits come into play. But much of that code can be shifted to the GPU.)

The tradeoff has almost exclusively been development time vs resource efficiency. Very few devs are graced with enough time to optimize something to the point of dealing with theoretical tradeoff balances of near optimal implementations.

Only if the software is optimised for either in the first place.

Ton of software out there where optimisation of both memory and cpu has been pushed to the side because development hours is more costly than a bit of extra resource usage.

You're thinking an algorithmic tradeoff, but this is an abstraction tradeoff.

Or just using less electron and writing less shit code.