use strict;
use warnings;
use feature 'say';

use Benchmark 'cmpthese';

use constant L => 1e5;

my @cases;

my $str = '1' x L;
push @cases, $str;

substr $str, rand L, 1 , '0' for 1 .. L;
push @cases, $str;
push @cases, '01' x ( L / 2 );

say $^V;

for my $s ( @cases ) {
    cmpthese -2, {
        count => sub { $s =~ tr/1// },
    }
}

__END__

v5.32.1
         Rate count
count 21711/s    --
         Rate count
count 21607/s    --
         Rate count
count 21348/s    --


v5.42.0
         Rate count
count 16271/s    --
        Rate count
count 2422/s    --
        Rate count
count 8136/s    --