#!/usr/bin/perl -w
use strict;
use Benchmark qw(cmpthese);

sub returnhashref {
 my %a=();
 for (1 .. 1000) {
   $a{$_}=$_;
 }
 return \%a;
}

cmpthese(-3,{
        'Ref' => sub { my $a=returnhashref(); return $$a{245}},
        'newhash' => sub { my $a=returnhashref(); my %a = %$a; return $a{245}}});

##</code><code>##

Benchmark: running Ref, newhash, each for at least 3 CPU seconds...
       Ref:  3 wallclock secs ( 3.24 usr +  0.01 sys =  3.25 CPU) @ 381.54/s (n=1240)
   newhash:  3 wallclock secs ( 3.21 usr +  0.00 sys =  3.21 CPU) @ 211.84/s (n=680)
         Rate newhash     Ref
newhash 212/s      --    -44%
Ref     382/s     80%      --