Finding source of web performance issue

Question

We are trying to track down a performance issue on a asp.net solution on windows 2008.

• The error page that has no database access and very little logic takes 10 sec. Other pages over 70 seconds.
• Performance drops noticeably only at high load
• total memory usage is low 5 GB of 16 available
• W3wp.exe using 2.5 GB
• several Connection_Dropped DefaultAppPool in the httperr file
• ca. 1500 connections, Asp.net queue length is 10000
• CPU usage is low

Anyone have an idea what I could check next?

Edit

I have now used VS 2010 to run a performance test against it in a test virtual server.

I ran 200 users with a stepped build up and no wait time.

The interesting thing was that the page time continued to increase even after the max number of users was reached. There did not appear to be any memory leaks, memory usage is flat. Time taken per page goes from 0.1 to 30.0 seconds.

All pages increase, the one that increases most is a get of the login page, no database access just a forms auth check to see if the user is logged in.

Answer 1

Upon reading your numbers (always answering too fast, am I?) I agree that you should probably profile the server-side first. See What Are Some Good .NET Profilers?

---

I suggest you use

• google chrome

It has excellent profiling tools (under developer tools, Ctrl-Shift-I on my installation). I peruse

• network
• profiles
• timeline

charts for the information.

Also, there is the more highlevel Y-Slow extension to Firefox. It is developed/used by yahoo and gives some rather to the point advice out of the box.

If you prefer Firefox, the Firebug extension comes pretty close to the Google developer tools

Answer 2

Ah. Wha about you just look it up?

Attach a profiler, make a profiling run, find out where the CPU spends itÄs time.

There are plenty of profilers around that offer 14 day free trials.

I wouldsay ou need more CPU - find out why ;)