[crubier]

It’s is first and foremost due to the “mathematically correct” (or at least “more correct”) resolution algorithms used in yarn. And it is further improved by the local caching of packages indeed. Note that you can even be in “zero install” mode with yarn, where you checkout in git this dependency cache, so you never have to “yarn install”, got checkout is enough to get everything. If npmjs.com falls down you wouldn’t be in any trouble.