https://github.com/dotnet/roslyn/issues/24941

Program.cs

using System;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Configs;
using BenchmarkDotNet.Diagnosers;
using BenchmarkDotNet.Running;

[Config(typeof(Config))]
public class Program
{
    public class Config : ManualConfig
    {
        public Config() => Add(MemoryDiagnoser.Default);
    }

    static void Main() => BenchmarkRunner.Run<Program>();

    static Func<int[]> Lambda(int[] xs)
    {
        return () => xs;
    }
    
    static Func<int[]> ExtensionMethod(int[] xs)
    {
        return xs.Identity;
    }

    private static int[] array = new int[0];

    [Benchmark]
    public void CreateDelegateLambda() => Lambda(array);

    [Benchmark]
    public void CreateDelegateExtensionMethod() => ExtensionMethod(array);

    [Benchmark]
    public void InvokeDelegateLambda() => Lambda(array).Invoke();

    [Benchmark]
    public void InvokeDelegateExtensionMethod() => ExtensionMethod(array).Invoke();
}

static class Extensions
{
    public static int[] Identity(this int[] xs) => xs;
}

summary.txt

BenchmarkDotNet=v0.10.11, OS=Windows 10 Redstone 3 [1709, Fall Creators Update] (10.0.16299.248)
Processor=Intel Core i5-2300 CPU 2.80GHz (Sandy Bridge), ProcessorCount=4
Frequency=2727543 Hz, Resolution=366.6303 ns, Timer=TSC
.NET Core SDK=2.1.300-preview2-008042
  [Host]     : .NET Core 2.0.5 (Framework 4.6.26020.03), 64bit RyuJIT
  DefaultJob : .NET Core 2.0.5 (Framework 4.6.26020.03), 64bit RyuJIT


                        Method |     Mean |     Error |    StdDev |  Gen 0 | Allocated |
------------------------------ |---------:|----------:|----------:|-------:|----------:|
          CreateDelegateLambda | 36.74 ns | 0.7785 ns | 0.9268 ns | 0.0280 |      88 B |
 CreateDelegateExtensionMethod | 18.38 ns | 0.5607 ns | 1.6532 ns | 0.0203 |      64 B |
          InvokeDelegateLambda | 37.26 ns | 0.9130 ns | 2.6776 ns | 0.0280 |      88 B |
 InvokeDelegateExtensionMethod | 23.83 ns | 0.6927 ns | 2.0424 ns | 0.0203 |      64 B |