Depends how seamlessly they can get devs to re-compile. ARM having to emulate x86 would be definitely slower. There is no reason to believe the per-watt perfor

Depends how seamlessly they can get devs to re-compile. ARM having to emulate x86 would be definitely slower. There is no reason to believe the per-watt performance of actual ARM code won't outperform equivalent x86 chips. i.e. an A(x) Macbook Air replacement could easily outperform the Intel variant at the same power envelope, based on the observed performance of the iPad pro my wife uses.