It is even 20 times faster if you use ATLAS 3.8:
Its DGEMM routine does the job in around 708,000,000 cycles, another factor of 2 faster (my
other numbers, also on a Core 2 (a Duo, but single threaded), were very similar to Ulrich's so
I can state this with some confidence). Of course there's been a lot of research and tweaking
to obtain this score.
ATLAS' SUMMARY.LOG reports for DGEMM:
Performance: 4846.05MFLOPS (302.88 percent of of detected clock rate)
and this is on a 1.6GHz Core 2 Duo, not 2.66GHz!
GOTOBLAS may also be worth looking at, for comparison. It looks more into TLB misses than