SELECT SQL_NO_CACHE COUNT(*) FROM orders AS o LEFT JOIN clients AS c ON(c.id=o.client_id);

SELECT SQL_NO_CACHE COUNT(*) FROM orders AS o LEFT JOIN accounts AS a ON(a.id=o.account_id);

SELECT SQL_NO_CACHE COUNT(*) FROM orders AS o
LEFT JOIN clients AS c ON(c.id=o.client_id)
LEFT JOIN accounts AS a ON(a.id=o.account_id); 

EXPLAIN SELECT SQL_NO_CACHE COUNT(*) FROM orders AS o LEFT JOIN clients AS c ON(c.id=o.client_id) LEFT JOIN accounts AS a ON(a.id=o.account_id);
+------+-------------+-------+------+---------------+------+---------+------+--------+-------+
| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows   | Extra |
+------+-------------+-------+------+---------------+------+---------+------+--------+-------+
|    1 | SIMPLE      | o     | ALL  | NULL          | NULL | NULL    | NULL | 101578 |       |
+------+-------------+-------+------+---------------+------+---------+------+--------+-------+

+--------------------------+---------------------------------------------+------+-----+---------------------+----------------+
| Field                    | Type                                        | Null | Key | Default             | Extra          |
+--------------------------+---------------------------------------------+------+-----+---------------------+----------------+
| id                       | int(11)                                     | NO   | PRI | NULL                | auto_increment |
| order_num                | varchar(255)                                | NO   | MUL | NULL                |                |
| type                     | enum('order','quote','invoice','drop_ship') | NO   | MUL | NULL                |                |
| status                   | varchar(255)                                | NO   | MUL | NULL                |                |
| cdate                    | datetime                                    | NO   |     | NULL                |                |
| mdate                    | datetime                                    | NO   |     | 0000-00-00 00:00:00 |                |
| is_machine               | tinyint(1)                                  | NO   |     | NULL                |                |
| warehouse_id             | mediumint(7)                                | NO   |     | NULL                |                |
| client_id                | int(11)                                     | NO   | MUL | NULL                |                |
| bill_as_shipping         | enum('no','yes')                            | NO   |     | no                  |                |
| tracking_num             | varchar(255)                                | NO   |     | NULL                |                |
| parent_order_id          | mediumint(7)                                | NO   | MUL | NULL                |                |
| parent_order_num         | varchar(255)                                | NO   |     | NULL                |                |
| is_drop_ship             | tinyint(1)                                  | NO   |     | NULL                |                |
| is_ship_complete         | tinyint(1)                                  | NO   |     | NULL                |                |
| is_quality_ctrl_required | tinyint(1)                                  | NO   |     | NULL                |                |
| account_id               | bigint(20)                                  | NO   | MUL | NULL                |                |
| cust_po                  | varchar(255)                                | NO   |     | NULL                |                |
| shipping_type            | varchar(255)                                | NO   |     | NULL                |                |
| ship_company             | varchar(255)                                | NO   |     | NULL                |                |
| is_commercial_invoice    | int(11)                                     | NO   |     | NULL                |                |
| customer_shipping_num    | varchar(255)                                | NO   |     | NULL                |                |
| ship_date                | datetime                                    | NO   |     | NULL                |                |
| confirm_date             | datetime                                    | NO   |     | NULL                |                |
| payment_terms            | varchar(255)                                | NO   |     | NULL                |                |
| is_3rd_trans             | tinyint(1)                                  | NO   |     | NULL                |                |
| note                     | text                                        | NO   |     | NULL                |                |
| total_discount           | decimal(10,2)                               | NO   |     | NULL                |                |
| sub_total                | decimal(10,2)                               | NO   |     | NULL                |                |
| sales_tax                | decimal(10,2)                               | NO   |     | NULL                |                |
| total_weight             | int(9)                                      | NO   |     | NULL                |                |
| estimated_shipping       | decimal(10,2)                               | NO   |     | NULL                |                |
| total                    | decimal(10,2)                               | NO   |     | NULL                |                |
| total_shipping           | decimal(10,2)                               | NO   |     | NULL                |                |
| history                  | text                                        | NO   |     | NULL                |                |
| order_id                 | mediumint(11)                               | NO   | MUL | NULL                |                |
| trade_show               | varchar(255)                                | NO   |     | NULL                |                |
| prefered_payment_method  | varchar(255)                                | NO   |     | NULL                |                |
| is_urgent                | int(1)                                      | NO   |     | NULL                |                |
| invoice_id               | int(11)                                     | NO   |     | NULL                |                |
| vendor_id                | int(11) unsigned                            | NO   |     | 0                   |                |
| plant                    | varchar(255)                                | NO   |     | NULL                |                |
| ship_handles             | varchar(255)                                | NO   |     | NULL                |                |
| ship_destination         | varchar(255)                                | NO   |     | NULL                |                |
| ship_charge              | decimal(10,2)                               | NO   |     | NULL                |                |
| ship_payer               | varchar(255)                                | NO   |     | NULL                |                |
| memo                     | text                                        | NO   |     | NULL                |                |
| created_by               | mediumint(7)                                | NO   |     | NULL                |                |
| actual_ship_date         | datetime                                    | NO   |     | NULL                |                |
| payment_credits          | decimal(10,2)                               | NO   |     | NULL                |                |
| invoiced_per             | int(5)                                      | NO   |     | 0                   |                |
| qty_hand_changed         | int(1)                                      | NO   |     | NULL                |                |
| production_date          | datetime                                    | NO   |     | NULL                |                |
| brand_name               | varchar(255)                                | NO   |     | NULL                |                |
| apparel_type             | varchar(255)                                | NO   |     | NULL                |                |
| is_manually_closed       | int(1)                                      | NO   |     | NULL                |                |
| is_not_ship_charge       | tinyint(1)                                  | NO   |     | 0                   |                |
| is_manager_check         | tinyint(1)                                  | NO   |     | 0                   |                |
| is_accounting_flag       | int(1)                                      | NO   |     | NULL                |                |
| cc_last4num              | char(4)                                     | NO   |     |                     |                |
| cc_expiration            | char(5)                                     | NO   |     |                     |                |
| shipping_term            | char(3)                                     | NO   |     |                     |                |
| location                 | varchar(255)                                | NO   |     |                     |                |
+--------------------------+---------------------------------------------+------+-----+---------------------+----------------+

+----------------------+------------------------------------+------+-----+---------------------+----------------+
| Field                | Type                               | Null | Key | Default             | Extra          |
+----------------------+------------------------------------+------+-----+---------------------+----------------+
| id                   | int(11)                            | NO   | PRI | NULL                | auto_increment |
| role                 | varchar(255)                       | NO   |     |                     |                |
| email                | char(50)                           | NO   |     |                     |                |
| password             | varchar(255)                       | NO   |     | NULL                |                |
| fname                | varchar(255)                       | NO   |     | NULL                |                |
| lname                | varchar(255)                       | NO   |     | NULL                |                |
| qb_initial           | varchar(255)                       | NO   |     |                     |                |
| salesteams_id        | int(10)                            | NO   |     | 0                   |                |
| region_id            | int(10)                            | NO   |     | 0                   |                |
| account_flag         | enum('yes','no')                   | NO   |     | no                  |                |
| address              | varchar(255)                       | NO   |     | NULL                |                |
| id_template          | mediumint(9)                       | NO   |     | 0                   |                |
| city                 | varchar(255)                       | NO   |     | NULL                |                |
| state                | varchar(255)                       | NO   |     | NULL                |                |
| zip                  | varchar(255)                       | NO   |     | NULL                |                |
| country              | varchar(255)                       | NO   |     | NULL                |                |
| phone                | varchar(255)                       | NO   |     | NULL                |                |
| mobile               | varchar(255)                       | NO   |     | NULL                |                |
| fax                  | varchar(255)                       | NO   |     | NULL                |                |
| status               | enum('active','blocked','deleted') | NO   |     | active              |                |
| last_login           | datetime                           | NO   |     | 0000-00-00 00:00:00 |                |
| count_login          | mediumint(9)                       | NO   |     | 0                   |                |
| cdate                | datetime                           | NO   |     | NULL                |                |
| remember_me          | varchar(255)                       | NO   |     | NULL                |                |
| filter_parms_orders  | text                               | NO   |     | NULL                |                |
| filter_parms_prodque | text                               | NO   |     | NULL                |                |
| allow_auto_printing  | tinyint(1) unsigned                | NO   |     | 0                   |                |
+----------------------+------------------------------------+------+-----+---------------------+----------------+

+----------------------------+--------------------------+------+-----+---------+----------------+
| Field                      | Type                     | Null | Key | Default | Extra          |
+----------------------------+--------------------------+------+-----+---------+----------------+
| id                         | int(11)                  | NO   | PRI | NULL    | auto_increment |
| status                     | enum('deleted','active') | NO   |     | active  |                |
| company_name               | varchar(255)             | NO   | UNI | NULL    |                |
| salutation                 | varchar(255)             | NO   |     | NULL    |                |
| fname                      | varchar(255)             | NO   |     | NULL    |                |
| lname                      | varchar(255)             | NO   |     | NULL    |                |
| is_accounting_flag         | int(11)                  | NO   |     | NULL    |                |
| country_id                 | int(11)                  | NO   |     | NULL    |                |
| default_payment_term       | varchar(255)             | NO   |     | NULL    |                |
| prefered_payment_method    | varchar(255)             | NO   |     | NULL    |                |
| default_shipping_number    | varchar(255)             | NO   |     | NULL    |                |
| notes                      | text                     | NO   |     | NULL    |                |
| cdate                      | datetime                 | NO   |     | NULL    |                |
| mdate                      | datetime                 | NO   |     | NULL    |                |
| tracking_num               | varchar(255)             | NO   |     | NULL    |                |
| orders_qty                 | int(11)                  | NO   |     | 0       |                |
| orders_total               | decimal(10,2)            | NO   |     | 0.00    |                |
| invoices_qty               | int(11)                  | NO   |     | 0       |                |
| invoices_total             | decimal(10,2)            | NO   |     | 0.00    |                |
| invoice_delivery_method    | varchar(255)             | NO   |     | NULL    |                |
| quotes_qty                 | int(11)                  | NO   |     | 0       |                |
| quotes_total               | decimal(10,2)            | NO   |     | 0.00    |                |
| ship_handles               | varchar(255)             | NO   |     | NULL    |                |
| ship_destination           | varchar(255)             | NO   |     | NULL    |                |
| ship_method                | varchar(255)             | NO   |     | NULL    |                |
| nafta_required             | tinyint(1)               | NO   |     | NULL    |                |
| non_standard_required      | varchar(255)             | NO   |     | NULL    |                |
| additional_haz             | varchar(255)             | NO   |     | NULL    |                |
| type                       | varchar(255)             | NO   |     | NULL    |                |
| phone                      | varchar(255)             | NO   |     | NULL    |                |
| phone2                     | varchar(255)             | NO   |     | NULL    |                |
| fax                        | varchar(255)             | NO   |     | NULL    |                |
| mssql_CompanyID            | int(11) unsigned         | NO   | MUL | 0       |                |
| mssql_CompanyName          | char(255)                | NO   |     |         |                |
| account_id                 | int(11)                  | NO   |     | NULL    |                |
| is_not_export_price        | int(11)                  | NO   |     | NULL    |                |
| is_applyotherdiscount      | int(11)                  | NO   |     | NULL    |                |
| is_applyotherdiscount_part | int(11)                  | NO   |     | NULL    |                |
| discountcustomer_id        | int(11)                  | NO   | MUL | NULL    |                |
| discountcustomer_part_id   | int(11)                  | NO   |     | NULL    |                |
| residential                | enum('yes','no','')      | NO   |     |         |                |
| tmp_field                  | varchar(255)             | NO   |     |         |                |
+----------------------------+--------------------------+------+-----+---------+----------------+