PSSCOR extension is a debugger extension which is super-set of SOS.DLL. It is used for debugging .NET issues with WinDBG, such as high memory / CPU usage, crashes, etc...
We have released PSSCOR2 for .NET 2.0 related issues before and we were using PSSCOR4 for a long time in Microsoft for .NET 4.0 related issues and now it is available for public download.
You can download PSSCOR4 extension from Microsoft download page:
Psscor4 Managed-Code Debugging Extension for WinDbg
Here is the overview taken from the same page:
managed call stacks (with source mappings)
managed exception information
what types are in the managed heap and their reference chain
which ASP.NET pages are running on which thread
the contents of the ASP.NET cache
and much more.
Enjoy PSSCOR4 🙂