DNS request timed out. timeout was 2 seconds.

Hi,  we are running Windows Server 2008 R2 Enterprise on our domain controller / Windows DNS server.

Nslookup from Win 7 clients for Internet DNS names result in two timeouts, like so:

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.

and then the query returns an answer. Query for the same name again does not time out; either because the record is in the client's resolver cache or the DNS server's cache.

We have two working (we think) forwarders in the DNS server, and the DNS server is configured to use Root Hints too, if Forwarders aren't there.

Any thoughts on why our name servers are slow to resolve Internet names?

I know this is a pretty broad question, but thanks for any suggestions!

Mike