Long User Syncronization when editing users in PS 2010

Hi

When editing users / resources in manage users, we experience long syncs in the queue. This is Project Server 2010. By long I mean about 20 minutes per user. On another non related environment on a test domain, its barely noticeable going through the queue (5 seconds maybe)

The system is specced well, and performs well otherwise?

Any help greatly received.