...has he controlled for network speed? Unless he's set up a local NPM caching proxy, he's going over the 'net for these packages. It'll take more than 1 datum before I believe this hype.
Many people have confirmed a major speed improvement. I've repeated this with an empty cache, primed cache and in different orders many times and have always got the same results. Having said that, a good number of people have reported seeing no speed improvement too.