This is a nice one. I would take another approach. The 65,000 is not really a problem with decent memory, so I would just read all in one swoop:

use SuperSplit;

$AoA = supersplit_open('|','\n',$filename);

no strict;
for $line ( @AoA ){
  $ecl_hash->{$line[0]}->{$line[1]}->{$line[2]}=@line[3..$#line];
}
my $sub_ecl = $ecl_hash->{$NETID}->{$date};
some_function( $sub_ecl->{$time} ) for $time (keys %$sub_ecl);
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This prevents you from grepping every item of your timearray, which takes quite some time indeed. The above returns something easy to process, but if you want more speed, the following is better and doesn't use supersplit:

open DATA, $filename;
my %ecl_hash;
my $str = "$NETID|$month/$date/$year";
while( <DATA> ){
  next if index($_,$str)<0;
  chomp;  
  my $item = (split '|' )[2];
  $ecl_hash{$item} = [] unless defined $ecl_hash{$item};
  push @$ecl_hash{$item}, $_;
}
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I use index here, because it's faster than matches.

Returns something similar, only the fields have not been separated into arrays. But maybe you don't even want to.

SuperSplit can be found here.

Cheers,

Jeroen
"We are not alone"(FZ)

Update: I ignored the fact that you want to search on the date/ID as well. Fixed in the last codeblock. Will be much faster, of course. What do you *really* want? You want to add an extra line to a report, with some sumary? You wanna make some graphs? Depending on the question, you can decide whether you want the whole thing read in, or just a little piece, or whether you'd better go and put everything in a database, as merlyn suggested...

Update2: after quite some CB, I think ImpalaSS'd better use the supersplit method and use the modified hash to access his data.