Slow PG Queries

LOG:  duration: 138.396 ms  execute <unnamed>: SELECT  "topic_custom_fields".* FROM "topic_custom_fields" WHERE "topic_custom_fields"."name" = 'import_id' AND "topic_custom_fields"."value" = '171368'  ORDER BY "topic_custom_fields"."id" ASC LIMIT 1

LOG:   duration: 10.007 ms  execute <unnamed>: SELECT  1 AS one FROM "email_logs" WHERE "email_logs"."post_id" = 5600348 AND "email_logs"."user_id" = 740596 AND "email_logs"."skipped" = 'f' LIMIT 1

LOG:  duration: 829.019 ms  execute <unnamed>: SELECT  COUNT(*) AS count_all, topic_tags.tag_id, tags.name AS topic_tags_tag_id_tags_name FROM "topic_tags" INNER JOIN "tags" ON "tags"."id" = "topic_tags"."tag_id" INNER JOIN "topics" ON "topics"."id" = "topic_tags"."topic_id" AND ("topics"."deleted_at" IS NULL) GROUP BY topic_tags.tag_id, tags.name  ORDER BY count_all DESC LIMIT 30


LOG:  duration: 16.837 ms  execute <unnamed>: SELECT COUNT(*) FROM "posts" WHERE ("posts"."deleted_at" IS NULL) AND (posts.post_type in (1,2,3)) AND (post_number > COALESCE((
	               SELECT last_read_post_number FROM topic_users tu
	               WHERE tu.user_id = 272438 AND tu.topic_id = 156687 ),0)) AND (reply_to_user_id = 272438 OR exists(
	            SELECT 1 from topic_users tu
	            WHERE tu.user_id = 272438 AND
	              tu.topic_id = 156687 AND
	              notification_level = 3
	            )) AND "posts"."topic_id" = 156687
              
LOG:  duration: 254.591 ms  execute <unnamed>: SELECT COUNT(*) FROM "post_actions" WHERE "post_actions"."post_action_type_id" = 2

LOG:  duration: 66.314 ms  execute <unnamed>: SELECT  "topics"."id" FROM "topics" LEFT OUTER JOIN "categories" ON "categories"."id" = "topics"."category_id" LEFT OUTER JOIN topic_users AS tu ON (topics.id = tu.topic_id AND tu.user_id = -1) WHERE (categories.id = 54 OR (categories.parent_category_id = 54 AND categories.topic_id <> topics.id)) AND (topics.archetype <> 'private_message') AND (COALESCE(categories.topic_id, 0) <> topics.id) AND "topics"."visible" = 't' AND ("topics"."id" != 60) AND (topics.deleted_at IS NULL) AND (COALESCE(tu.notification_level,1) > 0) AND (
	          NOT EXISTS (
	            SELECT 1
	              FROM category_users cu
	             WHERE cu.user_id = -1
	               AND cu.category_id = topics.category_id
	               AND cu.notification_level = 0
	               AND cu.category_id <> 54
	               AND (tu.notification_level IS NULL OR tu.notification_level < 2)
	          )) AND "topics"."closed" = 'f' AND "topics"."archived" = 'f' AND (topics.created_at > '2016-05-04 14:48:13.163378')  ORDER BY RANDOM() LIMIT 3000