I am suspecting that the line my $control_num = join ( ',', ('?') x @control ); where I am joining all the control numbers from the array "@control" is slowing down the query results.

Why worry about speed when you code doesn't work?

use strict;
use warnings;

my @control = qw ( 1 2 3 4 5 6 7 );
my $control_num = join ( ',', ('?') x @control ); 
print "cn=$control_num<<\n";

__DATA__
cn=?,?,?,?,?,?,?<<
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