Determining source of high processor usage

I've added ICQ# library (it's open source) to my application. But if I connect to ICQ server though it, it will increase usage of CPU (up to 30%). So something in ICQ# library is using CPU so much. But I don't know how to determinate what is it and reduce the usage of CPU.

Solution

If it's open source and you've added the code to your project; run it with a profiler attached.

http://www.jetbrains.com/profiler/
http://www.red-gate.com/products/dotnet-development/ants-performance-profiler/

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