They seem to be about the same. shift comes out slightly ahead in this test, perhaps because it simplifies the loop. 
#!/usr/bin/perl

use warnings;
use strict;

use Benchmark;

timethese(1_000_000, {
  'use_shift' => sub { sub_with_shift(0..9) },
  'use_list' => sub { sub_with_list(0..9) },
  'use_direct' => sub { sub_with_direct(0..9) },
});

sub sub_with_shift
{
  my $sum = 0;
  while (@_)
  {
    $sum += shift;
  }
  $sum;
}

sub sub_with_list
{
  my(@a)=@_;
  my $sum = 0;
  $sum += $_
    for @a;
  $sum;
}

sub sub_with_direct
{
  my $sum = 0;
  $sum += $_
    for @_;
  $sum;
}

[download]
Benchmark: timing 1000000 iterations of use_direct, use_list, use_shift...
use_direct:  7 wallclock secs ( 6.48 usr + -0.01 sys =  6.47 CPU) @ 154559.51/s (n=1000000)
  use_list: 10 wallclock secs ( 9.85 usr +  0.06 sys =  9.91 CPU) @ 100908.17/s (n=1000000)
 use_shift:  6 wallclock secs ( 6.48 usr +  0.01 sys =  6.49 CPU) @ 154083.20/s (n=1000000)

--
sgifford's Web page

In reply to Re^3: shift vs @_ by sgifford
in thread shift vs @_ by Zadeh

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