4.7.0 introduced a slow query

[c0ntax]

Expected Behavior

When displaying a post with an author's custom avatar, the code to generate the page should be performant

Current Behavior

get_custom_avatar() now uses attachment_url_to_postid(). This function searches the postmeta table by both meta_key and meta_value. Meta_value() cannot be indexed because it's a longtext so you end up with an inefficient query that can run on a page multiple times. It was adding anywhere between 0.8s and 1.5s to every page that displayed an author on my site.

Possible Solution

1. Introducing caching
2. Add a filter get_custom_avatar filter so that users's can introduce their own caching or do things differently
3. Roll back the code to 4.6.x?

Steps to Reproduce (for bugs)

1. Have a site with lots of posts and lots of metadata per post
2. Render an author with a custom avatar on a page
3. Look the Query Monitor tool bar light up

Context

I just want an author with a custom avatar on a page.

Your Environment

• Version used: 4.7.2
• Browser Name and version: N/A
• Operating System and version (desktop or mobile): Ubuntu 22.04.1-Ubuntu (Kernel 6.8.0-47-generic)