My understanding is that an inherent strict memory ordering that's common to x86-64 (AMD and Intel) makes it harder to get good memory efficiency. So all x86-6

My understanding is that an inherent strict memory ordering that's common to x86-64 (AMD and Intel) makes it harder to get good memory efficiency. So all x86-64's have a usable memory bandwidth that's a smaller fraction of the peak memory bandwidth. ARMs have a looser memory model and as a result often manage a much higher fraction of the peak memory bandwidth. Power as well.