FastExpressionCompiler

ExpressionParser.Parse() returns a plain LambdaExpression, so it can be compiled with any compiler instead of the built-in Compile(). FastExpressionCompiler is a drop-in, dependency-free replacement for LambdaExpression.Compile() that produces the same delegate much faster:

dotnet add package FastExpressionCompiler

using FastExpressionCompiler;

var lambda = ExpressionParser.Parse("Math.Pow(x, y) + 5", options);
var func = (Func<double, double, double>)lambda.CompileFast();

Benchmark

Expression	Compile()	CompileFast()	Speedup
Math.Pow(x, y) + 5	28.23 µs	2.24 µs	~12.6x
x switch { ... } with LINQ Select/Sum	180.92 µs	5.98 µs	~30x

The more complex the expression tree, the bigger the gap, since most of the reflection-emit overhead Compile() pays per node is avoided by CompileFast().

Benchmark source: CompileToDelegate.cs.