gistfile1.PL

#!/usr/bin/env perl
use Benchmark 'cmpthese';
use perl5i::latest;

my @things = map { rand_number() } (1 .. 100);
my @thangs = map { rand_number() } (1 .. 100);


sub ARRAY::diff_simple {
    my ($this, $that) = @_;

    my %seen = map { $_ => 1 } @$that;

    my @result = grep { not $seen{$_} } @$this;

    return wantarray ? @result : \@result;
}

cmpthese(
    -2,
    {
        perl5i      => sub { @things->diff( \@thangs ) },
        diff_simple => sub { @things->diff_simple( \@thangs ) },
    }
);

sub rand_number {
    return sprintf("%.3f", rand());
}

__END__
Before:
              Rate      perl5i diff_simple
perl5i      22.5/s          --       -100%
diff_simple 8675/s      38455%          --

After:
              Rate      perl5i diff_simple
perl5i      8330/s          --        -12%
diff_simple 9457/s         14%          --