Sure of course I followed that link. I've really got no idea what the horizontal axis is! But there is a huge cluster of results between 1x and 1.5x execution time.

And, the kind of code he is interested in is not necessarily the same as the kind of code I'm interested in. In fact I know it's not!

As one more data point, compiling my little benchmark with gcc, without any optimisation flag.

     1964ms gcc primes.c -o primes -O
     3723ms fil-c primes.c -o primes -O
     3753ms gcc primes.c -o primes
    16334ms fil-c primes.c -o primes

Fil-C with -O is almost identical to gcc without.