This release of Json.NET ships with many performance improvements, and is over 30% faster serializing and deserializing JSON compared to Json.NET 4.5.

Json.NET extends its performance lead over DataContractJsonSerializer and continues to be significantly faster than JavaScriptSerializer which is used by ASP.NET MVC.

Compiled Expressions on Windows 8 and Windows Phone 8

An additional performance improvement specific to Windows 8 and Windows Phone 8 is the switch from the serializer internally using latebound reflection to compiled expressions. In exchange for a small one off cost the first time a type is serialized, compiled expressions are considerably faster than latebound reflection and provide an additional speed boost to Json.NET on Win8 and WP8.

Changes

Here is a complete list of what has changed since Json.NET 5.0 Release 1.

• New feature - Added JsonWriter.SetWriteState to support inheritance from JsonWriter implementations
• Change - Changed .NET 4.5 portable library and WinRT library to use compiled expressions reflection
• Fix - Fixed error serializing non-generic types that implement IEnumerable

Links

Json.NET CodePlex Project

Json.NET 5.0 Release 4 Download – Json.NET source code and assemblies