Benchmark: timing 200000 iterations of Big, Pak, Str...
       Big: 10 wallclock secs (10.36 usr +  0.02 sys = 10.38 CPU) @ 19267.82/s (n=200000)
       Pak:  8 wallclock secs ( 9.81 usr +  0.03 sys =  9.84 CPU) @ 20325.20/s (n=200000)
       Str:  9 wallclock secs ( 8.30 usr +  0.02 sys =  8.32 CPU) @ 24038.46/s (n=200000)

##</code><code>##

sub mat_hash {
    my %cells;

    $cells{$_->[0]}{$_->[1]} = undef for @points;
    my $ncells = 0;
    $ncells += keys %{$cells{$_}} for keys %cells;
    $ncells == $npoints or die;
    exists $cells{$_->[0]}{$_->[1]} or die for @points;
    exists $cells{'notfound'} and die;
    exists $cells{'notfound2'} and die;
    exists $cells{'notfound3'} and die;
    return \%cells;
}

sub mat_look {
    my $cells = shift;
    exists $cells->{$_->[0]}{$_->[1]} or die for @points;
    exists $cells->{'notfound'} and die;
    exists $cells->{'notfound2'} and die;
    exists $cells->{'notfound3'} and die;
}

my $str_ref = str_hash();
my $big_ref = big_hash();
my $pak_ref = pak_hash();
my $mat_ref = mat_hash();

timethese 200000, {
   Str => sub { str_look($str_ref) },
   Big => sub { big_look($big_ref) },
   Pak => sub { pak_look($pak_ref) },
   Mat => sub { mat_look($mat_ref) },
};

##</code><code>##

#!/usr/bin/env perl

##</code><code>##

Benchmark: timing 200000 iterations of Big, Mat, Pak, Str...
       Big: 10 wallclock secs (10.06 usr +  0.02 sys = 10.08 CPU) @ 19841.27/s (n=200000)
       Mat:  8 wallclock secs ( 7.51 usr +  0.01 sys =  7.52 CPU) @ 26595.74/s (n=200000)
       Pak: 10 wallclock secs ( 9.63 usr +  0.01 sys =  9.64 CPU) @ 20746.89/s (n=200000)
       Str:  8 wallclock secs ( 7.78 usr +  0.02 sys =  7.80 CPU) @ 25641.03/s (n=200000)

Benchmark: timing 200000 iterations of Big, Mat, Pak, Str...
       Big: 10 wallclock secs (10.01 usr +  0.02 sys = 10.03 CPU) @ 19940.18/s (n=200000)
       Mat:  8 wallclock secs ( 7.52 usr +  0.01 sys =  7.53 CPU) @ 26560.42/s (n=200000)
       Pak: 10 wallclock secs ( 9.72 usr +  0.01 sys =  9.73 CPU) @ 20554.98/s (n=200000)
       Str:  8 wallclock secs ( 8.00 usr +  0.02 sys =  8.02 CPU) @ 24937.66/s (n=200000)

Benchmark: timing 200000 iterations of Big, Mat, Pak, Str...
       Big: 10 wallclock secs (10.05 usr +  0.01 sys = 10.06 CPU) @ 19880.72/s (n=200000)
       Mat:  8 wallclock secs ( 7.47 usr + -0.01 sys =  7.46 CPU) @ 26809.65/s (n=200000)
       Pak:  9 wallclock secs ( 9.66 usr +  0.02 sys =  9.68 CPU) @ 20661.16/s (n=200000)
       Str:  9 wallclock secs ( 8.09 usr +  0.01 sys =  8.10 CPU) @ 24691.36/s (n=200000)

##</code><code>##

$ perl -v | head -2 | tail -1
This is perl 5, version 26, subversion 0 (v5.26.0) built for darwin-thread-multi-2level