sub sub1    {   my $fh;
                    open $fh, 'vsfull.csv';
                    binmode $fh;

                    my @lines;

                    my $block; my $left = '';
                    while( read $fh, $block, 8192 ){

                        $block = $left . $block;

                        my $i = index $block, "\n";
                        while($i > 0){

                            push @lines, substr($block,0,$i);
                            substr($block,0,$i+1,'');
                            $i = index $block, "\n";

                        }

                        $left = $block;

                    }

                }

    sub sub2    {   my $fh;
                    my @lines;
                    open $fh, 'vsfull.csv';

                    while(<$fh>){ push @lines, $_ };

                }
sub sub3 { my $fh; open $fh, 'vsfull.csv'; my @lines = <$fh>; }
sub sub4 { my $fh; open $fh,'vsfull.csv';my @lines = readline($fh); }

#Hmark::
use Benchmark 'cmpthese';

cmpthese(
-3,
{ readbig => \&sub1,
  whilelp => \&sub2,
  better => \&sub3,
  butter => \&sub4,
});

__END__



Benchmark: running better, butter, readbig, whilelp, each for at least 3 CPU seconds...
    better:  3 wallclock secs ( 2.20 usr +  1.02 sys =  3.22 CPU) @ 372.36/s (n=1199)
    butter:  3 wallclock secs ( 2.17 usr +  1.04 sys =  3.21 CPU) @ 373.52/s (n=1199)
   readbig:  3 wallclock secs ( 3.01 usr +  0.12 sys =  3.13 CPU) @ 52.72/s (n=165)
   whilelp:  3 wallclock secs ( 2.17 usr +  1.02 sys =  3.19 CPU) @ 272.10/s (n=868)
          Rate readbig whilelp  better  butter
readbig 52.7/s      --    -81%    -86%    -86%
whilelp  272/s    416%      --    -27%    -27%
better   372/s    606%     37%      --     -0%
butter   374/s    609%     37%      0%      --