So there's this related open source project seeking to optimize the performance of Node.js apps running on IIS and hosting them on Azure. https://github.com/tjanczuk/iisnode/wiki We've seen some interesting performance gains by supplanting Node.js's HTTP implementation with the in-kernel HTTP stack, http.sys. http://tomasz.janczuk.org/2012/08/the-httpsys-stack-for-node...
Disclosure: I work for Microsoft. I personally found this interesting.