I can't find any further details on this claim. It wouldn't surprise me if it was true but benchmarks really do depend on the details. I want more info.

Skipping over the use of "Hello World!" in benchmarks is anyone actually surprised by this? Frameworks aren't a silver bullet. I don't think they were ever meant to be, especially when it comes to performance. There is nothing stopping you from going in to the framework code and optimising it or even taking functionality over to C++ if that's what you want.