use Benchmark qw (timethese);

timethese(10, {"regular" => \&regular, "reference" => \&reference});

sub regular {
	my %hash;
	for my $i (1 .. 100000) {
		$hash{$i} = $i;	
	}
}

sub reference {
	my $hash;
	for my $i (1 .. 100000) {
		$hash->{$i} = $i;	
	}
}

##</code><code>##

Benchmark: timing 10 iterations of reference, regular...
 reference:  8 wallclock secs ( 7.76 usr +  0.16 sys =  7.92 CPU) @  1.26/s (n=1
0)
   regular:  8 wallclock secs ( 7.20 usr +  0.14 sys =  7.34 CPU) @  1.36/s (n=1
0)
Benchmark: timing 10 iterations of reference, regular...
 reference:  9 wallclock secs ( 7.67 usr +  0.17 sys =  7.84 CPU) @  1.27/s (n=1
0)
   regular:  8 wallclock secs ( 7.23 usr +  0.08 sys =  7.31 CPU) @  1.37/s (n=1
0)

##</code><code>##

use Benchmark qw (timethese);

timethese(10, {"regular" => \&regular, "reference" => \&reference});

sub regular {
	my %hash;
	for my $i (1 .. 100000) {
		$hash{$i} = $i;	
	}
	helper(\%hash);
}

sub reference {
	my $hash;
	for my $i (1 .. 100000) {
		$hash->{$i} = $i;	
	}
	helper($hash);
}

sub helper {
	my $hash = shift;
}
##</code><code>##

Benchmark: timing 10 iterations of reference, regular...
 reference:  8 wallclock secs ( 7.72 usr +  0.14 sys =  7.86 CPU) @  1.27/s (n=1
0)
   regular:  9 wallclock secs ( 7.91 usr +  0.08 sys =  7.98 CPU) @  1.25/s (n=1
0)
Benchmark: timing 10 iterations of reference, regular...
 reference:  8 wallclock secs ( 7.70 usr +  0.11 sys =  7.81 CPU) @  1.28/s (n=1
0)
   regular:  9 wallclock secs ( 7.95 usr +  0.06 sys =  8.02 CPU) @  1.25/s (n=1
0)