If you are looking for high performance matrix/linear algebra/optimization on Intel processors, I'd look at Intel's MKL library.
MKL is carefully optimized for fast run-time performance - much of it based on the very mature BLAS/LAPACK fortran standards. And its performance scales with the number of cores available. Hands-free scalability with available cores is the future of computing and I wouldn't use any math library for a new project doesn't support multi-core processors.
Very briefly, it includes:
A downside is that the MKL API can be quite complex depending on the routines that you need. You could also take a look at their IPP (Integrated Performance Primitives) library which is geared toward high performance image processing operations, but is nevertheless quite broad.
Paul
CenterSpace Software ,.NET Math libraries, centerspace.net