#!/usr/bin/perl
                        
my %innerdata;
@innerdata{a..z} = a..z; 
 
my $data = {
        foo => {
                %innerdata
        },
        bar => {
                %innerdata
        }
};


sub foo {
        my $data = $_[0];
        for $key1 (keys %$data) {
                for $key2 (keys %{$data->{$key1}}) {
                        my $val = $data->{$key1}->{$key2}; 
                        # process $val;
                        # print $val;
                }
        }
}

         
sub bar {
        my $data = $_[0];
        for $key1 (keys %$data) {
                my $data2 = $data->{$key1};
                for $key2 (keys %$data2) {
                        my $val = $data2->{$key2};
                        # process $val;
                        # print $val;
                }
        }
} 

use Benchmark qw(cmpthese);

cmpthese(
        100000,
        {
                multiple_indirection => sub { foo($data) },
                reduced_indirection => sub { bar($data) },
        }
)