state-vs-my.pl

#!/usr/bin/perl

use feature qw{ say state };
use strict;
use warnings;
use Benchmark qw{:all};
use Carp;

my $str = "state declares a lexically scoped variable, just like my. However, those variables will never be reinitialized, contrary to lexical variables that are reinitialized each time their enclosing block is entered.";
my $len = length($str);

sub str { $str }

sub outside {
    die "outside" unless length( str() ) == $len;
}

sub use_my {
    my $str = str();

    die "use_my" unless length( $str ) == $len;
}

sub use_state {
    state $str = str();

    die "use_state" unless length( $str ) == $len;
}

timethese(
    10_000_000,
    {
        'outside'   => sub { outside() },
        'use my'    => sub { use_my() },
        'use state' => sub { use_state() },
    }
);

Benchmark: timing 10000000 iterations of outside, use my, use state...
   outside:  8 wallclock secs ( 7.09 usr +  0.00 sys =  7.09 CPU) @ 1410437.24/s (n=10000000)
    use my:  8 wallclock secs ( 8.50 usr +  0.00 sys =  8.50 CPU) @ 1176470.59/s (n=10000000)
 use state:  4 wallclock secs ( 3.03 usr +  0.00 sys =  3.03 CPU) @ 3300330.03/s (n=10000000)