Seema just had a great about using XPerf to troubleshoot CPU issues when using Silverlight. This can also be used in the same way to troubleshoot ASP.NET or IIS.
What can XPerf tell you? Seema answers that question, it can find out:
Is my app asking Silverlight to constantly spin on CPU cycles.
Whether one UI layout or design is more expensive than the other.
Whether the time is spent in drawing (agcore.dll), the plug-in’s interactions with (npctrl.dll), or in compilation/JIT (coreclr.dll)
How much is stretching/blending/rotating that video going to cost in terms of CPU cycles? How about if you encode it differently?
You can read more about XPerf and how to download and use it from Seema post here.
Note: The tools only work on Vista and Windows Server 2008.