WordPress MultiSite Admin Slow

After upgrading from 3 -> 4 the admin panel became utterly unusable. 20-30 seconds on any action.

Found - https://wordpress.org/support/topic/admin-back-end-slowfront-end-good#8

And for me :

Manually run /wp-admin/upgrade.php

UPDATE 25/1/2015 - Also had to do this for 4.0 -> 4.1 Upgrade