#! perl -slw
use strict;
use Time::HiRes qw[ time ];

sub timeit (&) {
    my $s=time;
    (shift)->();
    print "<", time - $s . ">";
}

our $l .= "$_\t" . (int rand 2) . "\n" for 1..1e6;  # linenumber TAB 0||1 RET

my $i=0; timeit { $i++ while ( $l =~ /\t1\n/g) }; print $i;

$i=0; timeit { $i = () = $l =~ /\t1\n/g }; print $i;

$i=0; timeit { $i = split /\t1\n/, $l }; print $i;

$i=0; timeit { local $/="\t1\n";open my $D,'<',\$l; $i++ while (<$D>) }; print $i;

$i = 0;
timeit {
    my $p = 0;
    ++$i while $p = 1 + index $l, "\t1\n", $p;
};
print $i;

__END__
C:\test>1032323
Use of implicit split to @_ is deprecated at C:\test\1032323.pl line 17.
<0.0966269969940186>
500737
<3.00464200973511>
500737
<0.204351902008057>
500738
<0.118543148040771>
500738
<0.0931870937347412>
500737