Microsoft.com Operations has been an early and active adopters of IIS 7.0 / Windows Server 2008. We actually started running a single server on the www.microsoft.com site back in June 2005. We set out to answer this question. Is IIS 7.0 / Windows Server 2008 more performant then IIS 6.0 / Windows Server 2003? We performed a side by side performance analysis on the www.microsoft.com site which was taking live internet traffic during peak traffic hours.
During this performance assessment we found that the CPU usage was higher on Microsoft Windows Server 2008 RTM servers, which is driven by the higher number of RPS the servers were handling. As mentioned below the hardware load balancers are sending more traffic to the Windows Server 2008 RTM servers (31% more RPS) as they are completing the outstanding web requests faster than the W2K3 SP2 server. A good metric listed below is the “efficiency” or “cost” of the number of requests per CPU cycle (RPS / CPU Utilization %). Using this metric, IIS 7.0/W2K8 RTM is over 10% more efficient then IIS 6.0/WS03 SP2 in handling live web platform traffic for the www.microsoft.com site.