performance hit for declaring attributes

Question

I understand that using reflection to process attributes can take a bit of time, but if I am not always using the attribute - is there much of a performance hit instantiating a class?

Given the small fictional snippet, if I am instantiating my class  often, do I have a performance hit because I have attributes on some entities within that class? I know some might respond saying if I am that worried about it perhaps I should redesign... but I am just curious about what people think. It is static metadata about the class, so I would hope not.

public class SomeClassThatICreateALot
{
    public enum MyEnum
    {
        [MySpecialAttribute("sample")]
        Val1,
        [MySpecialAttribute(42)]
        Val2,
        Val3,
    }
    // more code...
}

Answer 1

Nope, no performance impact whatsoever with unanalyzed attributes.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace ConsoleApplication71
{
    class Program
    {
        static void Main(string[] args)
        {
            int iterations = 10000000;

            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine("Iteration" + (i + 1));

                Console.WriteLine("With attributes: " + Test(() => new SomeClassThatICreateALot2(), iterations));
                Console.WriteLine("Without attributes: " + Test(() => new SomeClassThatICreateALot(), iterations));
            }
        }
        static long Test(Action action, int iterations)
        {
            Stopwatch sw = Stopwatch.StartNew();
            for (int i = 0; i < iterations; i++)
                action();
            long result = sw.ElapsedMilliseconds;
            return result;
        }
    }

    public class SomeClassThatICreateALot
    {
        [MySpecialAttribute(42)]
        public string Value { get; set; }

        [MySpecialAttribute(33)]
        public string AnotherValue { get; set; }
        // more code...
    }

    public class SomeClassThatICreateALot2
    {
        public string Value { get; set; }

        public string AnotherValue { get; set; }
        // more code...
    }

    public class MySpecialAttributeAttribute : Attribute
    {
        public MySpecialAttributeAttribute(string sample)
        {
           
        }

        public MySpecialAttributeAttribute(int sample)
        {

        }
    }
}


Output:

Iteration1
With attributes: 435
Without attributes: 225
Iteration2
With attributes: 208
Without attributes: 242
Iteration3
With attributes: 267
Without attributes: 305
Iteration4
With attributes: 237
Without attributes: 222
Iteration5
With attributes: 228
Without attributes: 237
Iteration6
With attributes: 235
Without attributes: 239
Iteration7
With attributes: 224
Without attributes: 225
Iteration8
With attributes: 230
Without attributes: 252
Iteration9
With attributes: 196
Without attributes: 213
Iteration10
With attributes: 211
Without attributes: 213

Pretty much even across the board.

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