I have a WCF client (running on Win7) pointing to a WebSphere service.

All is good from a test harness (a little test fixture outside my web app) but when my calls to the service originate from my web project one of the calls is extremely slow to deserialize (it takes up to 10 times longer) and not just the first time.

I can see from fiddler that the response comes back quickly but then the WCF client hangs on the response itself for more than a minute before the next line of code is hit by the debugger, almost if the client was having trouble deserializing. This happens only if in the response I have a given pdf string, base64 encoded chunked. If for example the service raises a fault (this pdf string is not there) then the response is deserialized immediately.

Again, If I send the exact same envelope through Soap-UI or from outside the web project all is good.

I am at loss - What should I be looking for and is there some config setting that might do the trick?

Any help appreciated!