The computer can do whatever it wants to adjust the mixture to meet emissions and power demand. It is still a mechanical loss. The engine has to work harder to produce the same rear wheel horsepower. Granted at lower RPM the losses are less and they increase with increased throttle opening. Still comes down to pulling air through a soda straw vs. pulling air through a paper towel tube. If you need to fill your lungs, which will be easier on you? And the thing with pumping losses (and all mechanical losses) is that they are there all the time- like rolling resistance from under-inflated tires. Constantly costing you a little bit more each mile you drive. If you don't think it is a problem, why do you EVER change your air filter.