Wcf service methods first calling takes too long time

Jun 14, 2010 at 7:06 PM

in my wpf project I use wcf service for getting service methods from the server.I'm using caliburn framework and the IoC container that is structure map.
in the first time  that the client side calls one of services from the server it takes too long time( about 40 second) but the query execution time is just 2 second. after this first calling, the other request and the rest of service method calling execute as rapid as I expect.
I dont know the reason and will appreciate if any body can help me to resolve this problem.