Benchmark: timing 30 iterations of REGEXP, SPLIT...
    REGEXP: 10 wallclock secs ( 9.73 usr +  0.25 sys =  9.98 CPU)
     SPLIT: 47 wallclock secs (47.20 usr +  0.28 sys = 47.48 CPU)
##</code><code>##

use strict;
use Benchmark;

timethese( 30, {
      REGEXP => 'UsingRegExp',
      SPLIT  => 'UsingSplit'
    }
);

sub UsingRegExp {
    my $file = 'r:\csv\test.csv';
    my $field;
    my $count = 0;
    open FH, $file or die "\n $file: $!\n";
    while ( <FH> ) {
        #  WANT 4TH FIELD. (NOTE: SOME FIELDS _MIGHT_ BE EMPTY.)
        ($field) = /^[^,]+,[^,]*,[^,]*,\s*([^,]+)\s*,/;
        $count++ if lc($field) eq "mapi";  #  IGNORE CASE
    }
    close FH or die "\n $file: $!\n";
}

sub UsingSplit {
    my $file = 'r:\csv\test.csv';
    my @record;
    my $count = 0;
    open FH, $file or die "\n $file: $!\n";
    while ( <FH> ) {
        @record = split /\s*,\s*/;
        $count++ if lc($record[3]) eq "mapi";  #  IGNORE CASE
    }
    close FH or die "\n $file: $!\n";
}