$s = 'kar'; $s x= 32749011;;
print length $s;;
98247033

$t = time; $s =~ m[karl] and ++$n for 1 .. 1; printf "%.9f\n", time() - $t;;
0.192370176

$t = time; $s =~ m[karl] and ++$n for 1 .. 10; printf "%.9f\n", ( time() - $t ) / 10;;
0.1929563999

$t = time; $s =~ m[karl] and ++$n for 1 .. 100; printf "%.9f\n", ( time() - $t ) / 100;;
0.192800162