asp.net - How to track IIS server performance

Question

I have a reoccurring issue where a customer calls up and complains that the web site is too slow. Specifically, if they are inactive for a short period of time, then go back to the site, there will be a minute-two minute delay before the user sees a response. (the standard browser is Firefox in this case)

I have Perfmon up and running, the cpu utilization is usually below 20% (single proc...don't ask). The database is humming along. And I'm pulling my hair out.

So, what metrics/tools do you find useful when evaluating IIS performance?

Answer 1

Hope this helps:
Best Practices for Speeding Up Your Web Site
Scaling Strategies for ASP.NET Applications
IIS Tuning
14 Rules for Faster-Loading Web Sites
Best practices for creating websites in IIS 6.0
Stanford Computer Cience - High Performance Web Sites
10 Tips for Writing High-Performance Web Applications
Writing High-Performance Managed Applications : A Primer
Nine tips for a healthy "in production" ASP.NET application
Speedy C#, Part 2: Optimizing Memory Allocations - Pooling and Reusing Objects
Memory Usage Auditing For .NET Applications
Troubleshooting HTTP Compression in IIS 6.0
Maximizing IIS Performance - 25 tips
Optimizing IIS 6.0 Performance
Page Speed - an open-source Firefox/Firebug Add-on
Performance Testing Guidance for Web Applications
Top 10 Performance Improvements in IIS 7.0
CHAPTER 6 Optimizing IIS 6.0 Performance
Performance Tuning Guidelines for Windows Server 2003 - Performance Tuning for IIS 6.0
ASP.NET Performance Tips
IIS 6.0 Tuning for Performance - by Peter A. Bromberg, Ph.D.
Improving .NET Application Performance and Scalability - by MS
Optimizing and Performance Tuning IIS 6.0
12 Steps To Faster Web Pages With Visual Round Trip Analyzer
Thread: IIS 6 performance tweak guide (draft)
CPU Settings for an Application Pool IIS6 e IIS7

Great improvements tips :
Running ASMX Web Services on STA Threads
Scale Net

Measure, measure, measure :
Load Test Your Site
Show Slow
Performance Monitor Wizard
Two Minute Drill: Introduction to XPerf
Suggested Performance Counters to Watch (IIS 6.0)

See what the best sites did :
Benchmarks
TOP 100

More resource :
Learn papers

My experience says:
- Enable compression (GZIP/Deflate) in IIS, for Static data. Simple to implement and with excellent results.
- if cpu is not your problem try to enable compression for dynamic data as well.