performance/mm2 This strikes me as not a particularly useful metric, or at least one only indirectly related to the stuff that actually matters. Performance/w

performance/mm2 This strikes me as not a particularly useful metric, or at least one only indirectly related to the stuff that actually matters. Performance/watt and performance/cost are the only metrics that really matter both to consumer and producer - performance/die size is only used as a metric because die size generally correlates to both of those. But comparing it between different manufacturers and different fabs strikes me as a mistake (although maybe it's just necessary because identifying actual manufacturing costs isn't possible?).