The issue is also reproducible with JBoss 7 and JBoss EAP6 on Windows Server 2003 R2 and is related to general TCP flow control issues of Windows Server.
The TCP flow control is slightly improved with Windows Server 2008 / 2008 R2 but still not as optimal as on Linux.
German article on TCP flow control on Windows(fee-based):
http://www.heise.de/artikel-archiv/ct/2012/10/176_kiosk
The recommendation for interationally used systems is to host either on Linux directly or to put an Linux-based reverse proxy (e.g. Apache) in front.