> 9. Transposing a matrix ... if you only use the transpose once. If instead it is going to be used multiple times, explicitly computing the transpose can be a

> 9. Transposing a matrix ... if you only use the transpose once. If instead it is going to be used multiple times, explicitly computing the transpose can be a huge performance boost. For dense matrices, it is typically used to exploit memory locality (i.e. to be prefetch- and cache-friendly). For sparse matrices (your point 8), the advantage can be even more pronounced, sometimes the difference between being able to exploit sparsity, or not.