a) that marketing page compares against a processor that is 4 years old, i.e. the processor in the 2011 MBA?

b) Intel has made new core i5's in the last 4 years (or even 3 years, 2 years, last year...)

c) we're not at a point where physics allows us to make hardware that consumes < 1/3 the power, but performs better, using the same manufacturing processes.