use Benchmark;

timethese(1, {
  'Trial1 While' => sub {
      open (FILE, "file2") or die "Can't open file:  $!\n";
      while (<FILE>) {
          last; # read one line and exit
      }
      close FILE;
  },
  'Trial2 Foreach' => sub {
      open (FILE, "file1") or die "Can't open file:  $!\n";
      foreach my $line (<FILE>) {
          last; # read one line and exit
      }
      close FILE;
  },
});

##</code><code>##

Benchmark: timing 1 iterations of Trial1 While, Trial2 Foreach...
Trial1 While:  0 wallclock secs ( 0.00 usr +  0.00 sys =  0.00 CPU)
Trial2 Foreach: 17 wallclock secs (10.77 usr +  1.56 sys = 12.33 CPU) @  0.08/s (n=1)