We recently moved our ASP.NET 4.0 application from Windows2003 x64/IIS 6 VM to a new Windows 2008 x64 RC2/IIS 7(7.5) VM. The resources are identical 4GB Memory, 4 CPU, both live on the same ESX host. I've attempted to match every conceivable iis configuration setting, caching, compression etc. between the two. Nevertheless, according to external performance monitoring by both alertsite and gomez, response times have doubled since cutover.
"Time to first byte" averages have increased by a few tenths of a second across the board. "Content" delivery time has increased by a full second across the board. "Full page download" has increased by several seconds across the board.
To confound matters further, we started with a two-node windows2008 farm, using ncache to cluster session, and a brocade load balancer, and saw a 2-5x increase in response times. We then dropped back down to just one server and bypassed the Load balancer to get back to a 2x increase in response times.
The fact that the load balancer made things worse, and that the bulk of the response time increase was in the content/base-page and fullpage download metrics, makes me think its something network related, or at least at the IIS level, where it simply isn't responding as fast as IIS6.
I'm hoping I've overlooked some key setting, because I can't fathom how upgrading both the OS and the doubling the resources (adding second node) resulted in worse performance.
I realize this isn't much information to go on, so I'm just looking for any suggestions about where to look or how to diagnose this. Suggestions on which perfmon counters to look at, what to look for and what they mean would help. Wild guesses welcome.