Here is an example of how the many variables can be replaced with a few arrays in the datafilla sub 
sub datafilla {
  for my $y (1..5){
    my $y_diff = ($f_mpy[$y] - $f_mpy[$y-1]) || 1;
    my $e_diff = ($f_mpe[$y] - $f_mpe[$y-1]);
    $popbyyer[$y] = $e_diff / $y_diff;
    $grand[$y] = $grand[$y-1] + ( ($e_diff<0) ? abs ($e_diff) : 0 );
  }
}

[download]
and a test page to check it works as expected 
#!/usr/bin/perl

use strict;
use CGI;
use CGI::Carp 'fatalsToBrowser';
our $VERSION = 3.11;

#INPUTS form values
my $q = CGI->new();
my $f_copyerr = $q->param('copyerr');
my $f_model   = $q->param('model');
my $f_initial = $q->param('initial');

my @f_mpy=(); # year
my @f_mpe=(); # estimate
foreach (0..5){
  $f_mpe[$_] = $q->param('mpe'.$_) || 0;
  $f_mpy[$_] = $q->param('mpy'.$_) || 1;
} 
$f_mpy[0]=0;

# CALCS
my @grand=(0);
my @popbyyer=($f_mpe[0]);

datafilla();
my $gener = (reverse sort @f_mpy)[0];
my $total = (reverse sort @f_mpe)[0] + $grand[5] - 1;

# RESULTS
my $results = results();

# print page
print "Content-type: text/html\n\n";
print qq(<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns='http://www.w3.org/1999/xhtml' xml:lang='en' lang='en'>
<head><meta http-equiv='Content-Type' content='text/html; charset=iso-
+8859-1' />
<meta http-equiv='Content-Style-Type' content='text/css' />
<style type='text/css'>
    td {padding: .5em; min-width:2.5em; }
</style>
<title>Model $f_model</title>
</head>
<body>
  $results
<p>Program Ver: $VERSION</p
</body>
</html>);

# datafilla
sub datafilla {
  for my $y (1..5){
    my $y_diff = ($f_mpy[$y] - $f_mpy[$y-1]) || 1;
    my $e_diff = ($f_mpe[$y] - $f_mpe[$y-1]);
    $popbyyer[$y] = $e_diff / $y_diff;
    $grand[$y] = $grand[$y-1] + ( ($e_diff<0) ? abs ($e_diff) : 0 );
  }
}

# calculation results
sub results {
  my $html = q{<table border="1">
<tr>
 <td>ix</td>
 <td>f_mpy</td>
 <td>f_mpe</td>
 <td>popbyyer</td>
 <td>grand</td>
</tr>};

  for my $ix (0..5){
    $html .= qq{
<tr>
 <td>$ix</td>
 <td>$f_mpy[$ix]</td>
 <td>$f_mpe[$ix]</td>
 <td>$popbyyer[$ix]</td>
 <td>$grand[$ix]</td>
</tr>};
  }
  $html .= qq{</table>
  gener = $gener<br/>
  total = $total<br/>};

  return $html;
}

[download]
poj

In reply to Re: This runs WAY too slow by poj
in thread This runs WAY too slow by Dandello

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