Even though Cassini is the default development web server in Visual Studio, Microsoft has provided a stand-alone option that also integrates with Visual Studio. IIS Express is almost exactly like the full IIS, only it is self-contained, it isn’t a service, and it doesn’t need admin rights for most tasks. We are going to walk through how to get it, how to configure it, and how to make the most of it without spending a lot of time on it.Article : Tim Corey on CodeProject
IIS 8 on Windows Server 2012 doesn’t have any fixed concurrent request limit, apart from whatever limit would be reached when resources are maxed.
However, the client version of IIS 8, which is on Windows 8, does have a concurrent connection request limitation to limit high traffic production uses on a client edition of Windows.
Source : Windows 8 / IIS 8 Concurrent Requests Limit - Scott Forsyth's Blog