I mean, we can compare it to mastercard: 74 billion transactions a year for mastercard vs 100 million a year for bitcoin. Mastercard revenue is 15 billion while bitcoin has 21 billion in annual mining fees. So mastercard processes 740 times as many transactions for 70% of the cost and I would argue the real cost is the revenue - operating income for their actual expenses to operate which is 7 billion so 1/3 the cost. That would make it 2,220 times as efficient.