{
    package LenTestC;
    use Encode;
    sub new {
        my $class = shift;
        my $self = '';
        return bless \$self, $class;
    }
    sub add {
        my ($self, $data) = @_;
        $$self .=  Encode::encode_utf8($data);
    }
    sub len {
        my $self = shift;
        return length $$self;
    }
}

##</code><code>##

use strict;
use warnings;
use feature 'say';
use feature 'state';
use utf8;
use Time::HiRes;

$|++;
my $chunk = '€' x 256;
my $td = Time::HiRes::time;
my $tf;
my $l;

say "with length()";
my $str = new LenTestA;
for my $n (1..15_000){
    state $count = 0;
    $str->add($chunk);
    $l = $str->len;

    $count++;
    if ($count % 1000 == 0){
        $tf = Time::HiRes::time;
        say sprintf "%12d L=%10d t=%f", $n, $l, $tf-$td;
        $td = $tf;
    }
}

$td = Time::HiRes::time;
say "\nwith a scalar";
$str = new LenTestB;
for my $n (1..15_000){
    state $count = 0;
    $str->add($chunk);
    $l = $str->len;

    $count++;
    if ($count % 1000 == 0){
        $tf = Time::HiRes::time;
        say sprintf "%12d L=%10d t=%f", $n, $l, $tf-$td;
        $td = $tf;
    }
}

say "\nwith encode/length()";
$str = new LenTestC;
for my $n (1..15_000){
    state $count = 0;
    $str->add($chunk);
    $l = $str->len;

    $count++;
    if ($count % 1000 == 0){
        $tf = Time::HiRes::time;
        say sprintf "%12d L=%10d t=%f", $n, $l, $tf-$td;
        $td = $tf;
    }
}

{
    package LenTestA;
    sub new {
        my $class = shift;
        my $self = '';
        return bless \$self, $class;
    }
    sub add {
        my ($self, $data) = @_;
        $$self .= $data;
    }
    sub len {
        my $self = shift;
        return length $$self;
    }
}
{
    package LenTestB;
    my $len;
    sub new {
        my $class = shift;
        my $self = '';
        return bless \$self, $class;
    }
    sub add {
        my ($self, $data) = @_;
        $$self .= $data;
        $len += length($data);
    }
    sub len {
        my $self = shift;
        return $len;
    }
}
{
    package LenTestC;
    use Encode;
    sub new {
        my $class = shift;
        my $self = '';
        return bless \$self, $class;
    }
    sub add {
        my ($self, $data) = @_;
        $$self .=  Encode::encode_utf8($data);
    }
    sub len {
        my $self = shift;
        return length $$self;
    }
}

##</code><code>##

with length()
        1000 L=    256000 t=0.510051
        2000 L=    512000 t=1.387138
        3000 L=    768000 t=2.304231
        4000 L=   1024000 t=3.246324
        5000 L=   1280000 t=4.112412
        6000 L=   1536000 t=5.093509
        7000 L=   1792000 t=5.957596
        8000 L=   2048000 t=6.853685
        9000 L=   2304000 t=9.705970
       10000 L=   2560000 t=9.114912
       11000 L=   2816000 t=9.906990
       12000 L=   3072000 t=11.083109
       13000 L=   3328000 t=12.515251
       14000 L=   3584000 t=12.456246
       15000 L=   3840000 t=13.957395

with a scalar
        1000 L=    256000 t=0.021152
        2000 L=    512000 t=0.021664
        3000 L=    768000 t=0.026949
        4000 L=   1024000 t=0.025393
        5000 L=   1280000 t=0.021830
        6000 L=   1536000 t=0.022298
        7000 L=   1792000 t=0.022668
        8000 L=   2048000 t=0.021850
        9000 L=   2304000 t=0.026711
       10000 L=   2560000 t=0.019835
       11000 L=   2816000 t=0.023417
       12000 L=   3072000 t=0.020025
       13000 L=   3328000 t=0.021878
       14000 L=   3584000 t=0.020085
       15000 L=   3840000 t=0.019838

with encode/length()
        1000 L=    256000 t=0.044469
        2000 L=    512000 t=0.037547
        3000 L=    768000 t=0.038610
        4000 L=   1024000 t=0.040161
        5000 L=   1280000 t=0.039640
        6000 L=   1536000 t=0.041329
        7000 L=   1792000 t=0.038967
        8000 L=   2048000 t=0.037193
        9000 L=   2304000 t=0.040582
       10000 L=   2560000 t=0.042830
       11000 L=   2816000 t=0.039120
       12000 L=   3072000 t=0.038353
       13000 L=   3328000 t=0.047136
       14000 L=   3584000 t=0.037603
       15000 L=   3840000 t=0.036865