First server response very slow. How come?

[cannibal]

When starting Notes client (5.06a) and opening the first database, it takes about 30-45 seconds!! before the domino server responds through TCP/IP (checking for servername at last know address .... on TCP/IP)
Once this is over the response is exellent(for every database that is opened). When closing Notes and starting the client again, the problem is there again.
Any ideas?

Thanks