my $statement = 'select a.foo, b.bar from local a,
 remote@my_database_link b where a.baz = b.baz (+) 
 and a.parm1 = 1 and b.parm2 = 2';
my $ary_ref = $dbhandle->selectall_arrayref($statement); # this executes in less than a second

$statement = 'select a.foo, b.bar from local a, 
 remote@my_database_link b where a.baz = b.baz (+) 
 and a.parm1 = ? and b.parm2 = ?';
my $sth = $dbhandle->prepare($statement);
my $rv = $sth->execute(1,2); # this takes 25+ seconds to execute
$ary_ref = $sth->fetchall_arrayref(); # this takes milliseconds