WCF WS-Trust binding (ws2007FederationHttpBinding) delay?

We have an BizTalk 2006 R2 solution with an federated WCF service (ws2007FederationHttpBinding). Things seem to work ok, but we experiencing some delay however.

From the WCF trace logs it seem to take about 30 - 45 sec delay to verify the security header of the incoming message. From the trace there is a delay processing security context tokens (action: http://docs.oasis-open.org/ws-sx/ws-trust/200512/RST/SCT). it from the point in the trace "Received a message over a channel" to "The security protocol verified the incoming message." we experience an delay (approx > 30 secs each time).

We've tried to set negotiateServiceCredential to false on both server and client without the desired outcome.

Does anybody have an idea what causing the delay?

Have to mention that the BizTalk server sits be开发者_如何学JAVAhind a firewall with limited access to resources (opened just for the client and the STS server)

I've been researching this issue also. I have it happening on a very simple wsHTTPbinding WCF service, but its the same issue. "Received a message over a channel" to "The security protocol verified the incoming message." are on different threads. mine have exactly 5mins and 30 seconds between them.