WP Admin extremely slow

Question

The WP back end of a site I\'m working on (It\'s a multisite) takes about 25 seconds to load.

Everything was working fine until yesterday and the front end still works p

Answer 1

I've seen this before where the admin pages are trying to poll external Wordpress sites for details of Wordpress upgrades, plugin updates and Wordpress news. If there's no proper access (because of firewall restrictions, bad DNS, etc) then the page has to wait for the HTTP requests (I think WP uses cURL) to timeout.

If you're still unable to identify the cause I'd recommend a catch-all solution of installing xdebug and profiling the page with webgrind, xcachegrind, etc