In one specific instance of a WordPress build the admin is incredibly slow, after checking the issue out with the Query Monitor plugin I notice that WordPress is running a handfull (~15) HTTP requests whenever you click around the admin panel.
These requests are all fired from the
wp_get_update_data() function, of which goes away to fetch plugin versions to check if the local plugins are up-to-date.
The issue here is this function is running for every request, and it's a big performance issue.
I've never had this on the hundreds of WordPress instances I've build before, does anyone know what could be the problem here?