As long as we're all tweaking the heck out of our benchmarks... ;-)

What I've noticed is the number of calls to these functions are not all the same. In the 'interval' function, we are calling gettimeofday, constructing an anonymous array, calling tv_interval, and destroying the array. Only one of these are we actually interested in. Meanwhile, both of the other two cases, we're calling *time twice. A completely different set of comparisons. I also eliminated the overhead of returning floats, what little that should be.

So, I thought I'd throw this into the mix. Put all the initialisation up front. Then see what happens.

#! /usr/bin/perl

use warnings;
use strict;

use Time::HiRes qw(time);
use Benchmark qw(:all) ;

my $interval0 = [Time::HiRes::gettimeofday()];
my $hires0    = Time::HiRes::time();
my $time0     = time();

cmpthese(-1,
         {
             'interval' => sub {
                 my $elapsed = Time::HiRes::tv_interval($interval0);
                 return;
             },
             'hires' => sub {
                 my $elapsed = Time::HiRes::time() - $hires0;
                 return;
             },
             'time' => sub {
                 my $elapsed = time - $time0;
                 return;
             },
         });
[download]

              Rate interval     time    hires
interval  685148/s       --     -79%     -80%
time     3340426/s     388%       --      -2%
hires    3398163/s     396%       2%       --
[download]

              Rate interval    hires     time
interval  971246/s       --     -77%     -78%
hires    4192706/s     332%       --      -3%
time     4327848/s     346%       3%       --
[download]