Slow behaviour on admin-ajax requests

[rmccue]

I'm working with a customer who is experiencing slowness on admin-ajax requests, which appears to be at least partially attributable to Authorship.

For example, on a query-attachments action (sorted by highest impact):

The specific query here doesn't seem too strange:

{
    "post_id": "1234",
    "query": {
        "post_mime_type": "image",
        "paged": "1",
        "posts_per_page": "80",
        "orderby": "date",
        "order": "DESC"
    },
    "action": "query-attachments"
}

However, this appears to be inefficiently querying the authors for these posts; there are 99 queries total, so approx 1 query per post (plus static overhead), where each query is:

SELECT DISTINCT t.term_id
FROM wp_4_terms AS t  INNER JOIN wp_4_term_taxonomy AS tt ON t.term_id = tt.term_id INNER JOIN wp_4_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id
WHERE tt.taxonomy IN ('authorship') AND tr.object_id IN (4321)
ORDER BY tr.term_order ASC

[johnbillion]

Are you seeing the same issue on the main Posts listing screen in the admin area (at wp-admin/edit.php)? I just checked another site and it is indeed performing a query to fetch the terms in the authorship taxonomy once for each post ID.

My understanding is that when fetching a list of posts, the list of terms for its taxonomies should be fetched at once and cached, but that is not happening.

[rmccue]

Looks like it, but harder to tell there. We're also hitting another bug with that which means the performance of the page is terrible (hierarchical post list tables are ungood)

[rmccue]

e.g. 10% of page load (but this isn't a particularly slow one):

This does have one query per author as well (50 queries to list 10 posts)