Symptoms
PA installation uses an Active Directory domain for provisioning Windows services. This domain has been split into two Active Directory sites and intersite replication has been configured between these sites. Now, Active Directory Domain Controller replication tasks are performed with a delay (up to 15 minutes).
Cause
There is a delay between intersite replication attempts and Active Directory Domain Controller replication tasks wait until intersite replication occurs.
Resolution
Configure instant intersite replication between these sites using the instruction from the Change Notification Between Sites section of the http://technet.microsoft.com/en-us/library/cc961787.aspx article.
Additional Info
For proper POA provisioning Active Directory sites should have fast replication. Maximum allowed replication latency typically shouldn't exceed 30 seconds. The actual number is highly installation-specific: it depends on provisioning tasks amount, number of Domain Controllers in both sites.