I'm on SharePoint 2010 using Claims authentication (Windows NTLM). When I go to the address book to search for a user, it takes a really long time to come back with any results. I only have 135 profiles. I've looked at my UPS service and all the settings look right. My search tree looks correct as well as the filter I have setup. I've done a full synch already. How should I go about troubleshooting this issue?
You need to target the nearest domain controller. This can be done by adding the subnet the SharePoint server resides on via Active Directory Sites and Services (must be completed by a Domain Admin). In this tool, you add the subnet the SharePoint servers reside on, then map it to a Site. The Site will have one or more domain controllers specified within it.
Using nltest.exe is simply a temporary fix and may change if the specified DC is restarted or if the SharePoint server is restarted.