Right. Ever since the late 90s ISA lost most of its importance on the high end. The most important factor for ISAs these days is probably code density since i

Right. Ever since the late 90s ISA lost most of its importance on the high end. The most important factor for ISAs these days is probably code density since instruction cache pressure can be an important factor in some workloads. Ease of decode still matters a bit. IIRC Bulldozer used 5-10% of its power budget on decode and Intel finds it worthwhile to have a cache of decoded instructions. But that's still a relatively small factor in the grand scheme of things.