Is there a way to manually set the receive window size (RWIN) in Windows Server 2008 R2 after disabling the "Receive Window Auto Tuning" feature?
It looks like it can be manually set, but Microsoft is only exposing it through Socket-Options. Which means specific applications opening sockets can set it, but you can't set it on an adapter like we used to do with Server 2000/2003.
A big hint on one of the 'best practices analyzer' errors. Apparently the TcpReceiveSize is ignored by 2008R2.
Down there at the end of the document is a section on doing some tcp testing with Server 2008. They use a specific utility, NTttcp, to do benchmarking. One of the options on that tool is to set window size options.
For IIS, you might be able to set a registry key to tell it to use a different value for that (http://support.microsoft.com/kb/820129). I don't know if that works for IIS7 or not.