If you wish to ignore Tanktalus's good advice and sweat the small stuff then a benchmark gives an answer. Normal benchmark caveats apply of course - like the benchmark may not indicate anything at all about your particular situation.

use strict;
use warnings;
use Benchmark qw(cmpthese);

use constant kHalfMax => 509; # Must be odd

my %Contracts = (1..4 * kHalfMax); # kHalfMax * 2 key/value pairs
my $key = kHalfMax;

cmpthese (-1,
        {
        lookup => \&lookup,
        refit => \&refit,
        }
    );


sub lookup {
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
    return if $Contracts{$key} == 1;
}


sub refit {
    my $ref = \$Contracts{$key};
    return if $$ref == 1;
    return if $$ref == 1;
    return if $$ref == 1;
    return if $$ref == 1;
    return if $$ref == 1;
    return if $$ref == 1;
    return if $$ref == 1;
    return if $$ref == 1;
}

[download]

Result:

           Rate lookup  refit
lookup 443125/s     --   -32%
refit  648621/s    46%     --

[download]

Note that the result is somewhat sensitive to the number of key/value pairs in the hash. 46% is about the largest difference I've seen.

Note too that at about 200 nano-seconds per access this tweak is unlikely to make much difference to most applications. Code clarity would be a much more important consideration!

DWIM is Perl's answer to Gödel

In reply to Re: Ref to hash entries are faster? by GrandFather
in thread Ref to hash entries are faster? by Wiggins

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