speed query execution

[frankz]

it is possible that the execute bit of a query (select) with 2 fields and the same with 8 fields (1000 records), the page load times with datagrid (url: file.php) range from 3 seconds to 30 seconds?

Code:

$sql = "SELECT idCliente,cognome,nome,codFisc,via,tel,telCell,note
		FROM clienti ORDER BY idCliente DESC ";
try {
    $stmt = $DB->prepare($sql);
    $stmt->execute();
    $results = $stmt->fetchAll();
} catch (Exception $ex) {
    printErrorMessage($ex->getMessage());
}
$returnArray = array();
if (count($results) > 0) {
	 foreach ($results as $rs) {
	 	$returnArray[] = $rs; 	
	 }
}
echo json_encode($returnArray);