When I build a release version of a project in Visual Studio 2008, it creates a .pdb file, e.g. for a simple WPF project it generates a .exe and .pdb file.
I've always understood .pdb files to be for debugging, so I would expect them to be in the Debug folder but not the Release folder.
And looking around at other StackOverflow questions, it doesn't seem that pdb files work well with teh Release version anyway.
Why are .pdb files generated in the Release folder by default and how can I turn that option off?
You are right. PDB files are for debugging but you may need to debug release builds too. Saving PDBs of released builds is very important when you want to debug a customer issue and you have the crash dump file related to that issue.
By the way, generating PDB files does not harm compiler optimizations. If you don't ship it to the customer, there will be no performance implications.
It depends on the project settings. Just happens that in Release version a .pdb is also generated by default. It will not hurt you - just don't ship it to the customer.
To skip its creation go to Linker->Debugging in project settings and set "Generate Debug Info" to "No".
来源：https://stackoverflow.com/questions/1642371/why-is-there-a-pdb-file-in-my-release-directory