I’ve been spending  a good deal of time focusing on performance issues lately. When your web properties count annual page views in the BILLIONS, it’s inevitable.

IIS 7 has great, often overlooked, granularity feature to help you hone performance and the IIS team continues to deliver in the performance space.

Check out ARR !

Application Request Routing (ARR) enables Web server administrators and hosting providers and to increase Web application reliability and scalability through rule-based routing and load balancing of HTTP server requests.

With ARR, administrators can optimize resource utilization for application servers to reduce management costs for Web farms and shared hosting environments.
 

http://www.iis.net/extensions/ApplicationRequestRouting