FastExpressionCompiler
A .NET library that compiles C# expression trees into delegates roughly ten to forty times faster than the built-in Expression.Compile, with a lightweight LightExpression alternative.
FastExpressionCompiler is a .NET library whose CompileFast extension method compiles C# expression trees into delegates far faster than the framework's own Expression.Compile, which the project attributes partly to Compile's use of a sandboxed dynamic method and anonymous assembly. Actual speed-up varies with the platform and with how complex an expression is, whether it has a closure, and whether it contains nested lambdas, but compiling also allocates noticeably less memory than Expression.Compile.
It ships as a small family of NuGet packages: FastExpressionCompiler itself, source-only and source-with-internal-visibility variants, and a separate LightExpression package that offers a lighter alternative to building System.Linq.Expressions trees in the first place. The project originated as part of the DryIoc dependency injection container.
It targets .NET 6 and newer, .NET Framework 4.7.2 and newer, and .NET Standard 2.0 and newer, and is released under the MIT license.