In terms of efficiency having mixed cores would be excellent. You can rely on ARM for lightweight system operations and where advanced instructions come to play

In terms of efficiency having mixed cores would be excellent. You can rely on ARM for lightweight system operations and where advanced instructions come to play like AVX-512 use x86-64. The problem as it was told to me was that you run into the different relationships they have with memory and hardware. I would love the boundary to be torn away. To idle at 5 watts while streaming and use 20watts while gaming ( a serious non-mobile game ).