How to update the delete user confirmation form?
On the Users (wp-admin/users.php) page, WordPress uses wp_dropdown_users() to generate the users drop-down menu you’re referring to, so I’d suggest using the wp_dropdown_users_args hook to filter the users query, e.g. to show only 1 result (or 10, but surely not 55k!) and then use JavaScript to add/load the other results. So in this answer, I’m … Read more