Оптимизация Django PostgresSQL

Имеется запрос

SELECT "shop_product"."id",
       "shop_product"."title",
       "shop_product"."slug",
       "shop_product"."is_active",
       "shop_product"."created_at",
       "shop_product"."is_hit",
       "shop_product"."is_new",
       "shop_product"."brand_id",
       "shop_product"."status",
       "shop_product"."image_copy",
       "shop_product"."description",
       "shop_product"."sku",
       "shop_product"."main_category_id",
       "shop_product"."properties_json",
       "shop_product"."width",
       "shop_product"."height",
       "shop_product"."length",
       "shop_product"."weight",
       "shop_product"."base_price",
       "shop_product"."price",
       "shop_product"."discount",
       "shop_brand"."id",
       "shop_brand"."slug",
       "shop_brand"."is_active",
       "shop_brand"."title",
       "shop_brand"."image",
       "shop_brand"."description",
       "shop_brand"."site",
       "shop_productmetadata"."id",
       "shop_productmetadata"."meta_title",
       "shop_productmetadata"."meta_description",
       "shop_productmetadata"."meta_author",
       "shop_productmetadata"."meta_robots",
       "shop_productmetadata"."product_id"
  FROM "shop_product"
  LEFT OUTER JOIN "shop_brand"
    ON ("shop_product"."brand_id" = "shop_brand"."id")
  LEFT OUTER JOIN "shop_productmetadata"
    ON ("shop_product"."id" = "shop_productmetadata"."product_id")
 WHERE "shop_product"."is_active"
 ORDER BY "shop_product"."title" ASC, "shop_product"."id" ASC
 LIMIT 15

И он работает 180-190 мс, но вовзвращает дубли.

Такой же запрос с DISTINCT работает в 8 раз дольше.

Как оптимизировать? Что можно сделать?

В таблице 600 000 товаров