Different hardware cache-hits differently for one. Level 3 BLAS functions like matrix on matrix products perform O(N^3) operations on O(N^2) data. The main wa

Different hardware cache-hits differently for one. Level 3 BLAS functions like matrix on matrix products perform O(N^3) operations on O(N^2) data. The main way BLAS boosts Level 3 functions is cache optimization which is hardware dependent. But optimization problems in general are not trivial for computers.