Slow performance with depth filter on larger site

@sakonn thanks for taking the time to report this.

Are you able to get a copy of the query from e.g. the views preview with SQL debugging turned on from the views settings?

If so, can you provide an explain for it?

I got the same problem, Detail:

SELECT node_field_data.langcode AS node_field_data_langcode, taxonomy_term_field_data_node__department.langcode AS taxonomy_term_field_data_node__department_langcode, node_field_data.published_at AS node_field_data_published_at, node_field_data.nid AS nid, taxonomy_term_field_data_node__department.tid AS taxonomy_term_field_data_node__department_tid
FROM
{node_field_data} node_field_data
LEFT JOIN {node__department} node__department ON node_field_data.nid = node__department.entity_id AND node__department.deleted = '0' AND (node__department.langcode = node_field_data.langcode OR node__department.bundle = 'article')
LEFT JOIN {taxonomy_term_field_data} taxonomy_term_field_data_node__department ON node__department.department_target_id = taxonomy_term_field_data_node__department.tid
INNER JOIN {node__category} node__category ON node_field_data.nid = node__category.entity_id AND node__category.deleted = '0' AND (node__category.langcode = node_field_data.langcode OR node__category.bundle = 'article')
WHERE (((node__category.category_target_id IN('10', '34333', '24', '23', '26', '19', '18', '27', '16', '13', '17', '14', '25', '48', '15', '20'))) AND (node_field_data.nid IN (SELECT tn.nid AS nid
FROM
{taxonomy_index} tn
LEFT OUTER JOIN {taxonomy_term__parent} th ON th.entity_id = tn.tid
LEFT OUTER JOIN {taxonomy_term__parent} th1 ON th.parent_target_id = th1.entity_id
LEFT OUTER JOIN {taxonomy_term__parent} th2 ON th1.parent_target_id = th2.entity_id
WHERE (tn.tid = '1263') OR (th1.entity_id = '1263') OR (th2.entity_id = '1263'))) AND (node_field_data.trash = '0')) AND ((node_field_data.status = '1') AND (node_field_data.type IN ('article')) AND (node_field_data.promote = '1'))
ORDER BY node_field_data_published_at DESC
LIMIT 9 OFFSET 0

After Delete the contextual filter, the speed faster several times.

SELECT node_field_data.langcode AS node_field_data_langcode, taxonomy_term_field_data_node__department.langcode AS taxonomy_term_field_data_node__department_langcode, node_field_data.published_at AS node_field_data_published_at, node_field_data.nid AS nid, taxonomy_term_field_data_node__department.tid AS taxonomy_term_field_data_node__department_tid
FROM
{node_field_data} node_field_data
LEFT JOIN {node__department} node__department ON node_field_data.nid = node__department.entity_id AND node__department.deleted = '0' AND (node__department.langcode = node_field_data.langcode OR node__department.bundle = 'article')
LEFT JOIN {taxonomy_term_field_data} taxonomy_term_field_data_node__department ON node__department.department_target_id = taxonomy_term_field_data_node__department.tid
INNER JOIN {node__category} node__category ON node_field_data.nid = node__category.entity_id AND node__category.deleted = '0' AND (node__category.langcode = node_field_data.langcode OR node__category.bundle = 'article')
WHERE (((node__category.category_target_id IN('10', '34333', '24', '23', '26', '19', '18', '27', '16', '13', '17', '14', '25', '48', '15', '20'))) AND ((node__department.department_target_id IN('1263', '70', '25981', '76', '116', '117', '62', '105', '72', '103', '78', '91', '99', '31431', '35625', '22973', '106', '75', '97', '126', '82', '83', '22968', '118', '80', '115', '22967', '69', '85', '108', '67', '95', '25606', '122', '92', '84', '114', '100', '65', '22972', '22257', '74', '66', '73', '119', '109', '124', '96', '64', '71', '107', '68', '104', '63', '90', '88'))) AND (node_field_data.trash = '0')) AND ((node_field_data.status = '1') AND (node_field_data.type IN ('article')) AND (node_field_data.promote = '1'))
ORDER BY node_field_data_published_at DESC
LIMIT 9 OFFSET 0