It's also worth noting that they're claiming a high perf/GHz, not a high perf. It's easy to shrink a chip by using slower but more compact libraries that don't

It's also worth noting that they're claiming a high perf/GHz, not a high perf. It's easy to shrink a chip by using slower but more compact libraries that don't increase gate size as much for larger fanout at the cost of a lower maximum frequency, like AMD's compact cores do. And lowering clock speeds mean that your main memory latency, measured in clock cycles, goes down increasing perf/GHz too.