FastestBinaryStream (nuget): Fluent interface for binary protocol implementation, aiming to prioritize runtime performance above all else.  An alternative to System.IO.MemoryStream + System.IO.BinaryReader & System.IO.BinaryWriter, and also System.Convert, that is better suited than the .NET (Core) implementations for performance-sensitive code (code for low-power platforms, high-volume/low-latency systems, games, etc.).
Keywords: Binary