> Oh, and x86_64 will be as power efficient as arm when one of the two entities will stop competing on having larger numbers and actually worry about power management.

Both Intel and AMD provide runtime power control so this is tunable. The last ~10% of performance requires far more than 10% of the power.

I remember hearing on one of the podcasts I listened to about the difference between the Apple power cores and efficiency cores.

The power ones have more execution units I think, and are allowed to run faster.

When running the same task, the efficiency ones are just ridiculously more efficient. I wish I had some link to cite.

The extra speed the power units are allowed is enough to tip them way over the line of exponential power usage. I’ve always known each bump in megahertz comes with a big power cost but it was eye-opening.