Thanks! I should mention that these tests were for a specific (highly tuned for the specific job) production HPC machine, so I don't know how this compares to

Thanks! I should mention that these tests were for a specific (highly tuned for the specific job) production HPC machine, so I don't know how this compares to a more generic setup - unfair of me to generalize the results to every matrix multiplication. We developed off the production machine in GFortran, and it worked very very well for us - didn't do timing tests there, but anecdotally, in development the difference was unnoticeable.