#!/usr/bin/perl

use warnings;
use strict;

use Benchmark;

use constant SIZE => 1000;

our @a1 = map { "a".$_ } (1..SIZE);
our @a2 = map { "A".$_ } (1..SIZE);

sub use_re
{
    my $count = 0;
    foreach my $i (@a1) {
        foreach my $j (@a2) {
            if ($i =~ /^\Q$j\E$/i) {
                $count++;
            }
        }
    }
    die unless $count == SIZE;
}

sub use_lc
{
    my $count = 0;
    foreach my $i (@a1) {
        foreach my $j (@a2) {
            if (lc $i eq lc $j) {
                $count++;
            }
        }
    }
    die unless $count == SIZE;
}

timethese(10, {
    RegExp => \&use_re,
    lc => \&use_lc,
});
[download]