Oh Ruggles...
http://9to5mac.com/2015/04/01/retina-macbook-performance-test/
http://www.primatelabs.com/blog/2010/10/macbookair_benchmarks-late-2010/
http://www.anandtech.com/show/9136/the-2015-macbook-review
http://browser.primatelabs.com/geekbench3/2299329
http://9to5mac.com/2015/04/25/first...op-model-rivals-1-4ghz-imac-2014-macbook-air/
http://www.everymac.com/systems/app...ok-air-core-2-duo-1.4-11-late-2010-specs.html
But I suppose you couldn't be bothered to look it up yourself, and would rather slap down a challenge with a one word post. His claim isn't wild or unsubstantiated, or not readily verifiable, he shouldn't have to cite sources for an established and well accepted position.
Also, the Core M is designed to be faster to turbo and faster to idle than its higher powered Core i siblings. This makes it extremely suitable for short burst tasks, even intensive ones, and equally unsuitable for long haul, sustained multicore tasks, like video encoding, or large complex compiling. That would be this Anandtech link.
http://www.anandtech.com/show/9117/analyzing-intel-core-m-performance
If we have to use a car metaphor, which I think we can all agree is not optimal - think of it as having a very short gear ratio on the same vehicle, whatever vehicle you can imagine, and the only difference is the gear ratios. With shorter gears throughout, it accelerates faster, is more responsive on the throttle, and has much more effective engine braking, but has a lower sustainable top speed because it runs out of revs in its final drive. This results in a car that feels very zippy and nimble around town, but is not really fit for long highway cruising.
Are there compromises? Yes there are, and if you want an all arounder processor that is a jack of all trades, but a master of none, then the U series Core i in your 11" MBA is great for you. And there is nothing wrong with that.
But if you value the portability and the lower heat and fanless design, and have usage requirements that actually favor the design choices made with the Core M and play to its strengths, then it is actually a very nice modern base for a good ultra portable laptop. And guess what - there is nothing wrong with that either.