Why would .NET code run slower on a 3GHz Xeon box versus a 1.2Ghz

[Guest]

We are an ASP and are converting our application from VB to VB.NET. Our web
farm is a mix of older dual processor 1.2GHz servers and newer dual processor
3.0GHz Xeon servers. When we originally got the new 3.0GHz boxes our VB code
thrived on them, dramatically outperforming our 1.2GHz boxes at every load
level. Now with the .NET code it appears that under light to moderate load,
our 1.2GHz servers are out performing our 3.0GHz boxes. Any ideas what may
be causing this?

 

[Guest]

After much ado, it appears part of our issue may be related to
hyperthreading. I might reccomend folks using spiffy new hyperthreading
chips try running a perf test with hyperthreading turned off.

The other part of the problem appears to be communicating with a Windows
2000 server for session information. Once we upgraded the box to 2003 we saw
a huge performacne gain. What is intersting about the win was that it
affected the performance of our .NET code more than our VB code? Odd.