Compiling this site from scratch on an 8-core machine, with make:

    real    2m24.231s
    user    1m46.904s
    sys     0m42.577s

With make -j8:

    real    0m36.224s
    user    3m14.642s
    sys     1m10.884s

With make -j9:

    real    0m27.458s
    user    2m25.657s
    sys     0m54.032s

with make -j10:

    real    1m41.305s
    user    2m24.265s
    sys     0m55.358s

With make -j16:

    real    1m7.558s
    user    2m46.179s
    sys     1m0.700s