my @array1 = (
   [ id1, ... 169 other fields ... ],
   [ id2, ... 169 other fields ... ],
   ... ~200k other records ...
);

my @array2 = (
   [ id2, ... 169 other fields ... ],
   [ id5, ... 169 other fields ... ],
   ... ~50k other records ...
);

##</code><code>##

my %array2 = map { $_->[0] => $_ } @array2;

##</code><code>##

for my $array1_rec (@array1) {
   my $array2_rec = $array2{ $array1_rec->[0] }
      or next;

   ... Change @$array1_rec based on values from @$array2_rec ...
}