C:\>perl test.pl
Benchmark: timing 100000 iterations of Mine, Particle, Yours...
      Mine:  5 wallclock secs ( 4.06 usr +  0.00 sys =  4.06 CPU) @ 24630.54/s (
n=100000)
  Particle:  8 wallclock secs ( 7.20 usr +  0.00 sys =  7.20 CPU) @ 13888.89/s (
n=100000)
     Yours: 25 wallclock secs (24.67 usr +  0.00 sys = 24.67 CPU) @ 4053.51/s (n
=100000)

C:\>

##</code><code>##

use Benchmark;

my $mine = <<'ME';
my $stuff = <<EOF;
boring boring boring
boring boring boring
boring boring boring
boring boring boring
boring boring boring
START
My wonderful super duper
yummy booty bag
information
END
boring boring boring
boring boring boring
boring boring boring
boring boring boring
boring boring boring
EOF

my ($good_stuff) = $stuff =~ m/(START.*END)/s;
# print $good_stuff;
ME

my $yours = <<'YOU';
my $stuff = <<EOF;
boring boring boring
boring boring boring
boring boring boring
boring boring boring
boring boring boring
START
My wonderful super duper
yummy booty bag
information
END
boring boring boring
boring boring boring
boring boring boring
boring boring boring
boring boring boring
EOF
my @lines = split("\n", $stuff); 
my $good_stuff; 
foreach(@lines){ 
   if(m/START/ .. m/END/) { 
      $good_stuff .= "$_\n";
   }
}
# print $good_stuff;
YOU

my $particle = <<'PARTICLE';
my $stuff = <<EOF;
boring boring boring
boring boring boring
boring boring boring
boring boring boring
boring boring boring
START
My wonderful super duper
yummy booty bag
information
END
boring boring boring
boring boring boring
boring boring boring
boring boring boring
boring boring boring
EOF
sub find_between_tags($$$) {
  my $string_to_parse = shift;
  my $start_tag = shift;
  my $start_pos = index $stuff, $start_tag; 
  return unless $start_pos > -1;            
  my $stop_tag = shift;
  my $stop_pos = index $stuff, $stop_tag;   
  $stop_pos > -1 ?                          
    return substr $stuff, $start_pos,       
      $stop_pos - $start_pos + length $stop_tag : 
    return substr $stuff, $start_pos, -1;   
}

my $good_stuff = find_between_tags($stuff, "START", "END");
# print $good_stuff;
PARTICLE

# prove they all work, uncomment the prints
# (we don't want to print when benchmarking)
# uncomment these evals
# eval $mine;
# eval $yours;

# Benchmark those suckers
timethese(100000,{
        'Mine'      => $mine, 
        'Yours'     => $yours,
        'Particle'  => $particle
        });