My environment: Windows Server 2008, IIE 7.0, ASP.NET I developed a Silverlight client. This

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Asked: May 19, 20262026-05-19T23:35:57+00:00 2026-05-19T23:35:57+00:00

My environment: Windows Server 2008, IIE 7.0, ASP.NET I developed a Silverlight client. This

0

My environment: Windows Server 2008, IIE 7.0, ASP.NET

I developed a Silverlight client.
This client gets updates from the ASP.NET host through a WCF web service.

We get 100% CPU usage and connection drops when we have a very low number of users (~50).
The server should clearly be able to handle a lot more than that.

I ran some tests on our DEV server and indeed 100 requests / s maxes out the CPU.
What’s odd is that even if the service is replaced by a dummy sending back hardcoded data the service still maxes out the CPU.
The thread count looked very low at about 20 so I thought there was some contention somewhere.

I changed all configuration options I could find to increase the worker threads (processModel, httpRuntime and the MaxRequestsPerCPU registry entry).
Nothing changed.

Then I stopped the IIS server and ran the web service as a console (removing all the ASP authentication references).
The service maxed out the CPU as well.

Then comes the magic part: I killed the console app and restarted IIS and now the service runs a 5-60% CPU with 100 requests / s and I can see 50+ worker threads.
I did the same thing on our preprod machine and had the same magic effect.
Rebooting the machines keeps the good behaviour.

So my question is: what happened to fix my IIS server? I really can’t understand what fixed it.

Cheers.