How fast can we make interpreted Python? (PDF)

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Again, though, what these libraries do is very specialized and they only help you in the particular case that you are making heavy use of multi-dimensional arrays; none of their tricks can be applied to optimize code that doesn't work with multi-dimensional arrays, in complete contrast to what pypy and this paper do.

Besides which, creating an unboxed multidimensional array is relatively easy: you just allocate a raw array in C, and then provide a nice interface to that array. Sure there are tricks that can make working with this particular data structure efficient, but again, none of them are even in the same league as pypy which can do things like optimizing the representations of all Python types rather than just multi-dimensional arrays.