#! /usr/bin/perl
# Used a 78MB file for test...
use Benchmark;

$infile = "lala.txt";
$outfile1 = "alal_stdio.txt";
$outfile2 = "alal_sys.txt";

$t0 = new Benchmark;
iotest1();
$t1 = new Benchmark;
print "the stdio code took:",(timestr timediff($t1,$t0)),"\n";

$t0 = new Benchmark;
iotest2();
$t1 = new Benchmark;
$td =
print "the sysread code took:",(timestr timediff($t1,$t0)),"\n";

sub iotest2 {
  open(IN,"< $infile");
  open(OUT,"> $outfile2");
  $buff = undef;
  while (sysread(IN,$in,8192)) {

    # This whole section could be redone...just soooo sleepy.
    #  Only able to think in a linear fashion atm.
    @in = split /\n/,$buff.$in;
    $buff = pop @in;
    if ($in =~ /\n$/io) {
      $buff .= "\n";
    }
    $out = join "\n",@in;

    # Do your thing....

    chomp($out);
    print OUT $out."\n";
  }
  print OUT $buff;
}

sub iotest1 {
  open(IN,"< $infile");
  open(OUT,"> $outfile1");
  while ($in = <IN>) {
    # do whatever....
    print OUT $in;
  }
}
# END Script

OUTPUT generally like:
the sysread code took:11 wallclock secs (10.52 usr +  0.57 sys = 11.09 CPU)
the stdio code took: 5 wallclock secs ( 4.45 usr +  0.89 sys =  5.34 CPU)

the stdio code took:11 wallclock secs (10.42 usr +  0.62 sys = 11.04 CPU)
the sysread code took: 5 wallclock secs ( 4.62 usr +  0.73 sys =  5.35 CPU)