Optimizing Dynamic Method Invokes in .NET

I recently had a lot of fun helping to optimize some RPC code that was using reflection to dynamically invoke methods in a C# application. Below are a list of implementations that we experimented with, and their performance.

1. Directly Invoking the Method
2. Using MethodInfo.Invoke
3. Using Delegate.DynamicInvoke
4. Casting to a Func
5. Casting a Delegate to Dynamic

Spoilers: Here are the results. (The tests for this can be see below.)

Name	First Call (Ticks)	Next Million Calls	Invoke Comparison
Invoke	1	39795	-
MethodInfo.Invoke	12	967523	x24
Delegate.DynamicInvoke	32	1580086	x39
Func Invoke	731	41331	x1
Dynamic Cast	1126896	85495	x2

Conclusion: Invoking a method or delegate directly is always fastest, but when you need to execute code dynamically, then (after the first invoke) the dynamic invoke of a delegate is significantly faster than using reflection.

Let's take a look at the test code...

Unit Tests

public class InvokePerformance

{

    public const int Iterations = 1000000;

    public static readonly object[] Args = {1, true};

    public static readonly TestClass Obj = new TestClass();

    public static readonly Type Type = typeof(TestClass);

    public static readonly MethodInfo Method = Type.GetMethod("TestMethod");

    private readonly ITestOutputHelper _output;

    public InvokePerformance(ITestOutputHelper output)

    {

        _output = output;

    }

    [Fact]

    public void Invoke()

    {

        var arg0 = (int) Args[0];

        var arg1 = (bool) Args[1];

        var sw0 = Stopwatch.StartNew();

        Method.Invoke(Obj, Args);

        sw0.Stop();

        var sw1 = Stopwatch.StartNew();

        for (var i = 0; i < Iterations; i++)

        {

            Obj.TestMethod(arg0, arg1);

        }

        sw1.Stop();

        _output.WriteLine(sw0.ElapsedTicks.ToString());

        _output.WriteLine(sw1.ElapsedTicks.ToString());

    }

    [Fact]

    public void MethodInfoInvoke()

    {

        var sw0 = Stopwatch.StartNew();

        Method.Invoke(Obj, Args);

        sw0.Stop();

        var sw1 = Stopwatch.StartNew();

        for (var i = 0; i < Iterations; i++)

        {

            Method.Invoke(Obj, Args);

        }

        sw1.Stop();

        _output.WriteLine(sw0.ElapsedTicks.ToString());

        _output.WriteLine(sw1.ElapsedTicks.ToString());

    }

    [Fact]

    public void DelegateDynamicInvoke()

    {

        var delType = Expression.GetDelegateType(typeof(int), typeof(bool), typeof(int));

        var del = Delegate.CreateDelegate(delType, Obj, Method);

        var sw0 = Stopwatch.StartNew();

        del.DynamicInvoke(Args);

        sw0.Stop();

        var sw1 = Stopwatch.StartNew();

        for (var i = 0; i < Iterations; i++)

        {

            del.DynamicInvoke(Args);

        }

        sw1.Stop();

        _output.WriteLine(sw0.ElapsedTicks.ToString());

        _output.WriteLine(sw1.ElapsedTicks.ToString());

    }

    [Fact]

    public void FuncInvoke()

    {

        var delType = Expression.GetDelegateType(typeof(int), typeof(bool), typeof(int));

        var del = (Func<int, bool, int>) Delegate.CreateDelegate(delType, Obj, Method);

        var arg0 = (int) Args[0];

        var arg1 = (bool) Args[1];

        var sw0 = Stopwatch.StartNew();

        del(arg0, arg1);

        sw0.Stop();

        var sw1 = Stopwatch.StartNew();

        for (var i = 0; i < Iterations; i++)

        {

            del(arg0, arg1);

        }

        sw1.Stop();

        _output.WriteLine(sw0.ElapsedTicks.ToString());

        _output.WriteLine(sw1.ElapsedTicks.ToString());

    }

    [Fact]

    public void DynamicCast()

    {

        var delType = Expression.GetDelegateType(typeof(int), typeof(bool), typeof(int));

        dynamic del = Delegate.CreateDelegate(delType, Obj, Method);

        dynamic arg0 = Args[0];

        dynamic arg1 = Args[1];

        var sw0 = Stopwatch.StartNew();

        del(arg0, arg1);

        sw0.Stop();

        var sw1 = Stopwatch.StartNew();

        for (var i = 0; i < Iterations; i++)

        {

            del(arg0, arg1);

        }

        sw1.Stop();

        _output.WriteLine(sw0.ElapsedTicks.ToString());

        _output.WriteLine(sw1.ElapsedTicks.ToString());

    }

    public class TestClass

    {

        public int TestMethod(int i, bool b)

        {

            return i + (b ? 1 : 2);

        }

    }

}

Enjoy,
Tom