It's not that difficult to be faster than MKL when you write the benchmarks. MKL is a general-purpose library, it does compromises to be good for most sizes. I

It's not that difficult to be faster than MKL when you write the benchmarks. MKL is a general-purpose library, it does compromises to be good for most sizes. If you care about the performance of specific sizes, you can write code to beat it on that very specific benchmark. Interestingly, BLIS does poorly at small sizes, which is the area where it is easiest to beat MKL at.