Как ускорить Opencart при большом кол-ве товаров?

Count: 46  Time=6.91s (317s)  Lock=0.05s (2s)  Rows=1.0 (46), 
  SELECT DISTINCT *, pd.name AS name, p.image, m.name AS manufacturer, 
  (SELECT price 
      FROM oc_product_discount pd2 
      WHERE pd2.product_id = p.product_id AND pd2.customer_group_id = 'S' 
            AND pd2.quantity = 'S' AND ((pd2.date_start = 'S' OR pd2.date_start < 'S') 
            AND (pd2.date_end = 'S' OR pd2.date_end > 'S')) 
       ORDER BY pd2.priority ASC, pd2.price ASC LIMIT N) AS discount, 
    (SELECT price 
       FROM oc_product_special ps 
       WHERE ps.product_id = p.product_id AND ps.customer_group_id = 'S' 
                  AND ((ps.date_start = 'S' OR ps.date_start < 'S') AND (ps.date_end = 'S' OR ps.date_end > 'S')) 
        ORDER BY ps.priority ASC, ps.price ASC LIMIT N) AS special, 
     (SELECT points 
        FROM oc_product_reward pr 
        WHERE pr.product_id = p.product_id AND customer_group_id = 'S') AS reward, 
     (SELECT ss.name 
         FROM oc_stock_status ss 
         WHERE ss.stock_status_id = p.stock_status_id AND ss.language_id = 'S') AS stock_status, 
      (SELECT wcd.unit 
          FROM oc_weight_class_description wcd 
          WHERE p.weight_class_id = wcd.weight_class_id AND wcd.language_id = 'S') AS weight_class, 
       (SELECT lcd.unit 
           FROM oc_length_class_description lcd 
           WHERE p.length_class_id = lcd.length_class_id AND lcd.language_id = 'S') AS length_class, 
        (SELECT AVG(rating) AS total 
            FROM oc_review r1 
            WHERE r1.product_id = p.product_id AND r1.status = 'S' 
            GROUP BY r1.product_id) AS rating, 
         (SELECT COUNT(*) AS total 
             FROM oc_review r2 
             WHERE r2.product_id = p.product_id AND r2.status = 'S' 
             GROUP BY r2.product_id) AS reviews, 
        p.sort_order FROM oc_product p 
    LEFT JOIN oc_product_description pd ON (p.product_id = pd.product_id) 
    LEFT JOIN oc_product_to_store p2s ON (p.product_id = p2s.product_id) 
    LEFT JOIN oc_manufacturer m ON (p.manufacturer_id = m.manufacturer_id) 
    WHERE p.product_id = 'S' AND p.status = 'S' AND p.date_available <= 'S' AND p2s.store_id = 'S'