List::Util is a part of 5.7.2 but not yet part of the 5.6 tree. It has several list processing functions coded in C that are useful.

For this simple program, using first() instead of (scalar grep) leads to a 47-fold increase in searching these lists of lists for a single value.

use Benchmark;
use List::Util qw(first);
use strict;

my @big_array = (1 .. 20);

my %x;

$x{$_} = \@big_array for (1 .. 100);

sub search_5_6 {
    scalar grep {
        scalar grep { $_ == 5 } @$_;
    } values %x;
}
sub search_5_7 { # Scalar-List-Utils is part of 5.7.2 and onward
     first {
        first { $_ == 5 } @$_;
    } values %x;
}

timethese(10000, {
    5.6 => \&search_5_6,
    5.7 => \&search_5_7
    }
          );

=head1
Benchmark: timing 10000 iterations of 5.6, 5.7...
       5.6: 47 wallclock secs (32.57 usr +  0.00 sys = 32.57 CPU) @ 30
+7.03/s (n\
=10000)
       5.7:  1 wallclock secs ( 0.57 usr +  0.00 sys =  0.57 CPU) @ 17
+543.86/s \
(n=10000)
=cut
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