The problem is that none of us agree what "Nazi efficiency" is. E.g. Mao Zedong killed a much larger number of people through his policies than the Nazis did,

The problem is that none of us agree what "Nazi efficiency" is. E.g. Mao Zedong killed a much larger number of people through his policies than the Nazis did, but letting your own population starve is not defined as "efficiency", rather the opposite of it. The grandparent apparently thinks of efficiency as in technology/engineering, and nothing that the Mongols used to kill people sounds very advanced to us. The Nazis had a very distinct way of using technology and bureaucracy for evil IMHO. And the OP seems to think in terms of economic efficiency.