Contention, poor performance, and deadlocks when you make Web service requests from ASP.NET applications
support.microsoft.com/kb/821268
in machine.config:
<system.net>
<connectionManagement>
<add address="*" maxconnection="500000"/>
</connectionManagement>
</system.net>
<system.web>
<processModel autoConfig="false" maxIoThreads="50" maxWorkerThreads="50" />