As is usually the case with language design, performance and optimization are often on the opposite side of the scale from code learn-ability and usability. More than likely, the "huge engine" would be some other burden the language has that he doesn't want in exchange for faster prototyping.
I'd actually say both Julia and Matlab are often quite decent on both learnability, usability (at least for their purpose -- especially as the library for Julia develops), and performance. Certainly, on par with other newly-designed languages. Sure, you can go faster with Fortran, but you can do that when you see that it is really needed...
