Performance of attracting interest is one of a very small number of well known sites running both Windows 2000 and Windows 2003 in a load balanced pool, and has become a tempting target for people to use as a straw in the wind towards the relative performance of the two operating systems. One person mailed us saying he thought that the Intel site's response time had slowed since Intel started using Windows 2003, and asked for confirmation and explanation.

The performance of shows a saw tooth formation, with some responses consistently longer than others. Matching up the response times with the corresponding server signatures actually does confirm that the responses served by Microsoft-IIS/6.0 are consistently longer than those served by Microsoft-IIS/5.0.

Analysing the response time graph more carefully shows that the connection time and time to serve the first byte are consistent across the two sets of servers, but the time to serve the complete request is significantly higher on the Microsoft-IIS/6.0 servers.

Response times in seconds from to 
London at Mid-day on 16 Jan 2003 by web server

It is important to appreciate that the difference need not be directly caused by the system software. Other plausible reasons could include;

  • The hardware specification of the Microsoft-IIS/5.0 machines may be faster than those running Microsoft-IIS/6.0
  • The configuration of the systems is likely to be different
  • From looking at the tcp/ip characteristics, we think it is likely that the front page is served dynamically, and  the migration of the application that generates the dynamic content may have introduced a performance penalty
  • The configuration of the local network at  Intel may have disadvantaged the Microsoft-IIS/6.0 machines in some way.