>perl -MTime::HiRes=time -MInline=C,"void foo(){}" -wE"$t=time;foo()for 1..1e8;say time-$t"
10.4052181243896

>perl -MTime::HiRes=time -wE"$t=time;sub foo(){}foo()for 1..1e8;say time-$t"
5.58481001853943