Thank you Laurel for your suggestion on further Improving the code . I have tried the steps you have suggested partially (Still working on a sloution using the Square root of the target Number)

Here is my code and the O/p yields right results and execution time is higher compared to ur solution . I will think about adding the Square root portion and update this thread 

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

sub prime_factors {
    my $num = shift;
    my $large_prime_found = 2;
    my @primes = ();
    my $odd = 1;
    my $i = 0;
   for ( my $y = $large_prime_found; $y <= $num;) {
      $i++;
     #print "Iteration : $i, y => $y, Num => $num LP => $large_prime_f
+ound, Arr Primes: @primes, Odd => $odd\n";
          if ($num % 2 == 0) {
              $num /= $large_prime_found;
              $large_prime_found = 2;
              push @primes, $large_prime_found;
              next;
         } else {
               $odd += 2;
           #if ($odd <=  sqrt($num)) {
               if ($num % $odd == 0 ) {
                   $large_prime_found = $odd;
                   $num /= $large_prime_found;
                   push @primes, $large_prime_found;
                   next;
               }
          #}
          }

  }

   return @primes;

}

$ time ./primes.pl
Number: 20 , Prime_Factors: => 2 2 5
Number: 48 , Prime_Factors: => 2 2 2 2 3
Number: 96 , Prime_Factors: => 2 2 2 2 2 3
Number: 7 , Prime_Factors: => 7
Number: 69 , Prime_Factors: => 3 23
Number: 33 , Prime_Factors: => 3 11
Number: 13195 , Prime_Factors: => 5 7 13 29
Number: 600851475143 , Prime_Factors: => 71 839 1471 6857

real    0m0.011s
user    0m0.005s
sys    0m0.004s

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In reply to Re^4: Avoid keeping larger lists in Memory by pr33
in thread Avoid keeping larger lists in Memory by pr33

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