Hi,
I wiresharked this and found out that it does do DNS-queries to couple verisign.com addresses and www.download.windowsupdate.com
On my environment DNS worked fine, but the problem was that it tries to establish http-connection to some verisign -addresses and that caused the
slowness.
... just wondering, WHY... 
anyway I just create *.verisign.com to my DNS-server and pointed those out to my horizion server so it replies with http..