Slow queries when rendering logging tab

With logging on the change log tab is really slow to render. On a medium-large DB (300,000 contacts and 1 million activities) I'm seeing 3 queries taking 5 seconds or more each. These turn out to be badly written

"INSERT IGNORE INTO civicrm_temp_civireport_logsummary SELECT entity_log_civireport.id as log_civic
rm_entity_id, entity_log_civireport.log_action as log_civicrm_entity_log_action, 'log_civicrm_activity_for_target' as log
_civicrm_entity_log_type, entity_log_civireport.log_user_id as log_civicrm_entity_log_user_id, entity_log_civireport.log_date as log_civicrm_entity_log_date, modified_contact_civireport.display_name as log_civicrm_entity_altered_contact, modified_contact_civireport.id as log_civicrm_entity_altered_contact_id, entity_log_civireport.log_conn_id as log_civicrm_entity_log_conn_id, modified_contact_civireport.is_deleted as log_civicrm_entity_is_deleted, altered_by_contact_civireport.display_name as altered_by_contact_display_name
FROM log_civicrm_activity entity_log_civireport

INNER JOIN log_civicrm_activity_contact fk_table ON (entity_log_civireport.id = fk_table.activity_id AND fk_table.record_type_id = 3)
INNER JOIN civicrm_contact modified_contact_civireport
ON (fk_table.contact_id = modified_contact_civireport.id )
LEFT JOIN civicrm_contact altered_by_contact_civireport
ON (entity_log_civireport.log_user_id = altered_by_contact_civireport.id) WHERE ( modified_contact_civireport.id = 278486 ) AND (entity_log_civireport.log_action != 'Initialization') GROUP BY entity_log_civireport.log_conn_id, entity_log_civireport.log_user_id, EXTRACT(DAY_MICROSECOND FROM entity_log_civireport.log_date), entity_log_civireport.id "

Feb 24 14:46:53 [info] ** QUERY DONE IN 5.963534 seconds. 63 row(s)s subject to insert action

INSERT IGNORE INTO civicrm_temp_civireport_logsummary SELECT entity_log_civireport.id as log_civicrm_entity_id, entity_log_civireport.log_action as log_civicrm_entity_log_action, 'log_civicrm_activity_for_assignee' as log_civicrm_entity_log_type, entity_log_civireport.log_user_id as log_civicrm_entity_log_user_id, entity_log_civireport.log_date as log_civicrm_entity_log_date, modified_contact_civireport.display_name as log_civicrm_entity_altered_contact, modified_contact_civireport.id as log_civicrm_entity_altered_contact_id, entity_log_civireport.log_conn_id as log_civicrm_entity_log_conn_id, modified_contact_civireport.is_deleted as log_civicrm_entity_is_deleted, altered_by_contact_civireport.display_name as altered_by_contact_display_name
FROM log_civicrm_activity entity_log_civireport

INNER JOIN `imba_civicrm_log`.log_civicrm_activity_contact fk_table ON entity_log_civireport.id = fk_table.activity_id AND fk_table.record_type_id = 1
INNER JOIN civicrm_contact modified_contact_civireport
ON (fk_table.contact_id = modified_contact_civireport.id )
LEFT JOIN civicrm_contact altered_by_contact_civireport
ON (entity_log_civireport.log_user_id = altered_by_contact_civireport.id) WHERE ( modified_contact_civireport.id = 278486 ) AND (entity_log_civireport.log_action != 'Initialization') GROUP BY entity_log_civireport.log_conn_id, entity_log_civireport.log_user_id, EXTRACT(DAY_MICROSECOND FROM entity_log_civireport.log_date), entity_log_civireport.id "

Feb 24 14:46:58 [info] ** QUERY DONE IN 5.195286 seconds. 1 row(s)s subject to insert action

$Query = string(1509) "INSERT IGNORE INTO civicrm_temp_civireport_logsummary SELECT entity_log_civireport.id as log_civicrm_entity_id, entity_log_civireport.log_action as log_civicrm_entity_log_action, 'log_civicrm_activity_for_source' as log_civicrm_entity_log_type, entity_log_civireport.log_user_id as log_civicrm_entity_log_user_id, entity_log_civireport.log_date as log_civicrm_entity_log_date, modified_contact_civireport.display_name as log_civicrm_entity_altered_contact, modified_contact_civireport.id as log_civicrm_entity_altered_contact_id, entity_log_civireport.log_conn_id as log_civicrm_entity_log_conn_id, modified_contact_civireport.is_deleted as log_civicrm_entity_is_deleted, altered_by_contact_civireport.display_name as altered_by_contact_display_name
FROM `log_civicrm_activity entity_log_civireport

INNER JOIN `log_civicrm_activity_contact fk_table ON entity_log_civireport.id = fk_table.activity_id AND fk_table.record_type_id = 2
INNER JOIN civicrm_contact modified_contact_civireport
ON (fk_table.contact_id = modified_contact_civireport.id )
LEFT JOIN civicrm_contact altered_by_contact_civireport
ON (entity_log_civireport.log_user_id = altered_by_contact_civireport.id) WHERE ( modified_contact_civireport.id = 278486 ) AND (entity_log_civireport.log_action != 'Initialization') GROUP BY entity_log_civireport.log_conn_id, entity_log_civireport.log_user_id, EXTRACT(DAY_MICROSECOND FROM entity_log_civireport.log_date), entity_log_civireport.id "

Feb 24 14:47:04 [info] ** QUERY DONE IN 5.717618 seconds. 90 row(s)s subject to insert action