SBCL quicker than C?
I considered the spectral norm benchmark and compared the C and SBCL implementations.
I started re-running the tests without any further optimization and the results were similar to the ones reported with C beating SBCL by a factor of 2. (for the C optimization used, see here).
Then, I noticed that there was no =(declaim (optimize (speed 3) (safety 0) (space 0)))= in the SBCL file! I've added it and rerun the test. Here are my results:
N=500 gcc 0.15u 0.00s 0.17r sbcl 0.08u 0.02s 0.21r N=3000 gcc 5.60u 0.00s 5.69r sbcl 5.18u 0.01s 5.41r N=5500 gcc 18.81u 0.01s 19.12r sbcl 17.42u 0.02s 17.76r
SBCL implementation is actually faster than C! You can find the code for the tests here.