But how many parameters do you have anyway? If you look at the total program, is the loop going to be the bottleneck? Optimizing something that only takes a small part of the running time isn't very useful.

Here are some benchmarking results, which show that it's the method call being the bottleneck.

Abigail

       
#!/usr/bin/perl
            
use strict;
use warnings 'all';

use Benchmark::Sized;  # To be released...
use CGI;

use vars qw /$cgi/;

$cgi = CGI -> new;
   
my $stats = sized_timethese
    run_for     =>  1,
    start_size  =>  2,
    end_size    =>  4096,
    steps       =>  12,
    seed        =>  sub {
        $main::cgi -> delete_all;
        foreach (1 .. $_ [0]) {$main::cgi -> param ($_, $_)}
    },
    code        =>  {
        map1    =>
           'my %input = ();
            map  {$input {$_} = $main::cgi -> param ($_)} $main::cgi -
+> param',
        map2    =>
           'my %input =
            map {$_ => $main::cgi -> param ($_)} $main::cgi -> param',
        grep    =>
           'my %input = ();
            grep {$input {$_} = $main::cgi -> param ($_)} $main::cgi -
+> param',
        for     =>
           'my %input = ();
            $input {$_} = $main::cgi -> param ($_) for $main::cgi -> p
+aram'
    }
;

print_timed $stats, type => 'sized';

__END__
Runs/second:
Size       for    grep    map1    map2
   2:  9569.16 9774.55 9773.64 9569.16
   4:  5749.09 5749.09 5749.09 5688.57
   8:  3200.00 3169.81 3169.81 3140.19
  16:  1689.62 1659.26 1644.04 1644.04
  32:   872.73  837.38  845.28  853.33
  64:   439.45  426.67  425.71  430.77
 128:   222.22  216.22  214.29  216.50
 256:   110.19  106.67  106.73  105.71
 512:    53.40   51.38   51.38   50.93
1024:    25.69   24.53   24.53   24.07
2048:    12.50   11.93   11.82   11.54
4096:     6.31    5.94    5.83    5.61
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