Of course it is dead slow. You are opening, reading and closing each file for 10 * 60 = 600 times to get the sum for each second. You should read each file once and store the sums in a hash, keyed by the timestamp, like so: 

my %SMPP_count;

foreach my $file (@files)
{               
        open (FILE,"$file"); 
        while(<FILE>)   
        {               
                next unless /\b(?:GSM|SMPP)\b/; # avoid uninteresting 
+lines
                chomp;
                my @ary  = (split /\s|\|/, $_) [3,21,24];
                my $time = (split ' ', $ary[0])[4]; # first element is
+t timestamp, right?
                $SMPP_count{$time}++ if  $ary[0] eq $stamp and $ary[1]
+ eq "Submit" and $ary[2] =~ /(GSM|SMPP)/;
        };
}

# now iterate over the keys of the hash to make up your sums

for my $time ( sort keys %SMPP_count) {
    my $sum = $SMPP_count{$time};
    ...
}

[download]
perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re^5: using system command in regex by shmem
in thread using system command in regex by ravi45722

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