// cache system on getIsoById

classes/Country.php

@@ -92,6 +92,8 @@ class CountryCore extends ObjectModel
 		)
 	);
 
+    protected static $cache_iso_by_id = array();
+
 	protected $webserviceParameters = array(
 		'objectsNodeName' => 'countries',
 		'fields' => array(
@@ -208,13 +210,15 @@ class CountryCore extends ObjectModel
 	*/
 	public static function getIsoById($id_country)
 	{
-		$result = Db::getInstance(_PS_USE_SQL_SLAVE_)->getRow('
+        if (!isset(Country::$cache_iso_by_id[$id_country]))
+        {
+            Country::$cache_iso_by_id[$id_country] = Db::getInstance(_PS_USE_SQL_SLAVE_)->getValue('
             SELECT `iso_code`
             FROM `'._DB_PREFIX_.'country`
-			WHERE `id_country` = '.(int)$id_country
+            WHERE `id_country` = '.(int)($id_country));
-		);
+        }
 
-		return $result['iso_code'];
+		return Country::$cache_iso_by_id[$id_country];
 	}
 
 	/**