Remove unneeded sanitize term in `populate_terms` method

[spacedmonkey]

In [52836] ( #37189 ) the WP_Term_Query class was converted to just get ids and then convert those ids into WP_Term objects using get_term. But in the case where fields all_with_object_id is passed, this results in lots of calls to sanitize_term. These calls can be extensive and effect performance. all_with_object_id expects an object as a result, but does not necessarily need to be sanitized.

Trac ticket: https://core.trac.wordpress.org/ticket/58327

@felixarntz @joemcgill

Basically, get_term has some overhead attached to it. It has filters and after the filtering, it rerun the sanitisation. When all_with_object_id is requsted ( in update_object_term_cache ), you only need the raw object. update_object_term_cache only needs to the term ids, so those filters and sanitisation are not needed. The sanitisation is run in WP_Term::get_instance() meaning no break in B/C. But as update_object_term_cache run on every WP_Query, which can be run 10+ times on many themes, ( block template parts, menus etc ), these calls to get_term can really really mount up, resulting in thousands of calls to sanative_term and apply_filters.

This change is a side effect of ​https://github.com/WordPress/wordpress-develop/commit/4a9f5fe3be47914b3f2b30aaf863761335cf1ad2 , resulting in the unexpected overhead.

@spacedmonkey I think get_post had the same overhead and was solved by bypassing the filtering when possible:

​https://github.com/WordPress/wordpress-develop/blob/5ebe28966e5decbe1862c147bf98db0d8094038e/src/wp-includes/class-wp-post.php#L251-L253

Would this work in WP_Term::get_instance instead of changing WP Query? The terms are cached with raw sanitization so this should save a bunch of work for sites using get_term() too.

src/wp-includes/class-wp-term.php

@@ -182 +182 @@
                 }
 
                 $term_obj = new WP_Term( $_term );
-                $term_obj->filter( $term_obj->filter );
+                if ( empty( $term_obj->filter ) || 'raw' !== $term_obj->filter ) {
+                        $term_obj->filter( $term_obj->filter );
+                }
 
                 return $term_obj;
         }

@peterwilsoncc I have created a PR based on your idea. ​https://github.com/WordPress/wordpress-develop/pull/5260. This solution multiple problems, of double sanitation. Please take a look.

[spacedmonkey]

Marking this as a duplicate as this issue will be fixed in #58329.

Fixed in ​https://github.com/WordPress/wordpress-develop/commit/c1247f6a278bd6a5fec799964177743b5d26a2aa