Serialization and immutable collections do mix in .NET, but only if you look to third party libraries like JSON.NET and protobuf-net.
Newtonsoft’s JSON.NET has received a pair of architectural updates to make it easier to use in projects that involve third party libraries. The two features are known as DefaultSettings and Extension Data.
The Json.NET project just released version 4.5 of their JSON framework for .NET which includes many new features and a dramatic speed enhancement. InfoQ recently spoke with Json.NET creator James Newton-King about the new release and the project as a whole.
Json.NET is claiming to offer better serialization and deserialization performance than any of the major serializers in .NET including BinaryFormatter. It even performs well against the remarkably fast DataContractSerizalier.