#!/perl/bin/perl
#
# bench.pl --
use strict;
use warnings;
use diagnostics;
use Benchmark qw(:all);

my $str = '|0' x (shift @ARGV || 100_000);

sub caseone {
    $_ = $str;
    s/.//;
}

sub casetwo {
    $_ = $str;
    substr($_,0,1) = '';
}

sub casethree {
    $_ = $str;
    $_ = reverse $_;
    chop;
    $_ = reverse $_;
}

sub casefour {
    $_ = $str;
    $_ = substr($_,1);
}

cmpthese(-2, {
    'regex' => 'caseone',
    'substr_mod' => 'casetwo',
    'reverse' => 'casethree',
    'susbtr_copy' => 'casefour',
});
[download]

# string length 2 * 10:
                 Rate     reverse       regex  substr_mod susbtr_copy
reverse      797484/s          --        -29%        -30%        -41%
regex       1125463/s         41%          --         -1%        -16%
substr_mod  1131927/s         42%          1%          --        -16%
susbtr_copy 1344489/s         69%         19%         19%          --


# string length 2 * 100_000:
              Rate     reverse susbtr_copy       regex  substr_mod
reverse     1385/s          --        -51%        -60%        -80%
susbtr_copy 2847/s        106%          --        -17%        -58%
regex       3437/s        148%         21%          --        -49%
substr_mod  6771/s        389%        138%         97%          --

# with 2 * 1e7:
              Rate     reverse susbtr_copy       regex  substr_mod
reverse     8.61/s          --        -54%        -58%        -81%
susbtr_copy 18.7/s        117%          --         -8%        -58%
regex       20.4/s        137%          9%          --        -54%
substr_mod  44.6/s        418%        139%        119%          --
[download]

The speed doesn't really depend on the perl version (I tried 5.8.8 and 5.10.0).