Query takes nearly 6 secs. Is it ok? I switched on Devel logging on site (shop on Drupal Commerce), went to Shop->Orders and saw that 

3818.231 views_plugin_query_default::execute P A E
SELECT commerce_order.order_id AS order_id, commerce_order.order_number AS commerce_order_order_number, commerce_order.uid AS commerce_order_uid, commerce_order.created AS commerce_order_created, users_commerce_order.name AS users_commerce_order_name, users_commerce_order.uid AS users_commerce_order_uid, commerce_order.status AS commerce_order_status, 'commerce_order' AS field_data_commerce_order_total_commerce_order_entity_type FROM commerce_order commerce_order LEFT JOIN users users_commerce_order ON commerce_order.uid = users_commerce_order.uid LEFT JOIN recently_read recently_read_commerce_order ON commerce_order.order_id = recently_read_commerce_order.entity_id LEFT JOIN commerce_payment_transaction commerce_payment_transaction_commerce_order ON commerce_order.order_id = commerce_payment_transaction_commerce_order.order_id WHERE (( (commerce_order.status NOT IN (:db_condition_placeholder_0, :db_condition_placeholder_1, :db_condition_placeholder_2, :db_condition_placeholder_3, :db_condition_placeholder_4, :db_condition_placeholder_5)) )) ORDER BY commerce_order_created DESC LIMIT 100 OFFSET 0
default

2422.621 views_plugin_pager::execute_count_query P A E
SELECT COUNT(*) AS expression FROM (SELECT 1 AS expression FROM commerce_order commerce_order LEFT JOIN users users_commerce_order ON commerce_order.uid = users_commerce_order.uid LEFT JOIN recently_read recently_read_commerce_order ON commerce_order.order_id = recently_read_commerce_order.entity_id LEFT JOIN commerce_payment_transaction commerce_payment_transaction_commerce_order ON commerce_order.order_id = commerce_payment_transaction_commerce_order.order_id WHERE (( (commerce_order.status NOT IN (:db_condition_placeholder_0, :db_condition_placeholder_1, :db_condition_placeholder_2, :db_condition_placeholder_3, :db_condition_placeholder_4, :db_condition_placeholder_5)) ))) subquery


Is it normal that on site with 3000 items and 7000 orders it takes so much time to form orders view in admin interface?

Site is hosted on server, Xeon E5-2609x2 (2.4 Ghz), 16 Gb DDR-3 memory
Just looking at the query, the obvious culprit is the recently_read module. The join that is added to the query is fully unindexed:

LEFT JOIN recently_read recently_read_commerce_order ON commerce_order.order_id = recently_read_commerce_order.entity_id


The query doesn't really make sense, so I assume the Views integration for this module needs work.