I would add more information about this issue:
Behavior: Usually adding a new port-group (EPG) takes 1 second. With this fault it will takes 15 minutes or it will added no more (Fault606347)
Cisco suggests this: https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvh93166/?rfs=iqvred
BUT no up-links names was changed.
Solution should be delete and re-create DVS but it is destructive!!!
Update: The Cisco release say this - see attached file Rel4.1
Anyone have many folders in vcenter?
I solved the case.
One of 3 APIC was slow to push configuration to vcenter.
This faulty APIC was replaced with new one and I fixed the issue.
Another solution could be: If you are in multi-pod configuration and you have 1 APIC and vcenter in POD1 and others 2 APICs in the POD 2, pay attention to DON'T have time delay between APIC1 in POD1 and the others in POD2.
In this case you must have the leader APIC near to vcenter.