Julia faster on Mac OSX than in linux?

(back on topic)

This probably means that OpenBLAS does not correctly identify your new processor, so it is not using the best SIMD instructions. (Prescott is the fallback architecture.)

You could build Julia to use MKL for BLAS, or you can try to force OpenBLAS to use the Haswell target. (See the README at the main Julia repo for instructions.)