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Adding caching to database queries in WP_Query
WordPress 6.1 includes an improvement to how database queries are performed in the WP_Query class, resulting in database queries will be cached. This means that if the same database query is run more than once, the result will be loaded from cache. For those using persistent object caching, this will mean that the database query will not run again until caches are invalidated, resulting in far fewer queries to the database. Sites using in-memory caching will also see the benefit of not repeating these queries, though the performance improvement will not be as significant.
For those doing custom development, please ensure that you are using core functions such as wp_insert_post to add posts to the database. These functions are well-maintained, and by using them, you ensure that caches are correctly invalidated. If you are updating the database directly, then it is strongly recommended that you call the clean_post_cache function after updating the database row.