Exclude copied Visual Studio PDB (debug) and XML (intellisense) files in copied output directory on Release builds.

<Project ...>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    ...
    <AllowedReferenceRelatedFileExtensions>
      <!-- Prevent default XML and PDB files copied to output in RELEASE.
           Only *.allowedextension files will be included, which doesn't exist in my case.
       -->
      .allowedextension

      <!-- or set to "-" to exclude all files -->
      -
    </AllowedReferenceRelatedFileExtensions>
  </PropertyGroup>