cmpthese -1, {
    shared => q[ my $x : shared; ++$x for 1 .. 1e6 ],
 nonshared => q[ my $x         ; ++$x for 1 .. 1e6 ],
};;
            (warning: too few iterations for a reliable count)

          s/iter    shared nonshared
shared      1.31        --      -89%
nonshared  0.141      834%        --