use strict;
use warnings;

my @alphabet = ('a'..'z', 'A'..'Z', ' ');

sub random_string {
    my $length = int shift;
    return join '', map { @alphabet[int rand(@alphabet)] } 1..$length;
}

my $re = join '|', map { random_string(5+rand(10)) } 1..500;

my $target = random_string(1e2);

use Benchmark qw(timethis);

timethis(100_000, sub { $target =~ m/$re/ })