If you're Worried About Performance, Avoid Using Type Initializers (aka static constructors)

I'm currently trying to write a highly scalable web application (using C# and .NET Framework 2.0), so, I simply trying to squeeze every drop of performance of the CPU, the DB .. etc. I'm doing a lot of performance testing to everything I use in my application. In my application, I'm using static constructors heavily as they seem to make things easier, well, this is until I realized that they really affect performance! Actually, I discovered this by accident while doing another test. I wanted to test the performance of using nested static classes vs. using singletons, in the process I used a couple of static constructors in the classes (see the code below), the point was to use the static constructor to initiate the variable used for holding the singleton object reference so that we can remove the lazy loading if condition which I expected it would improve performance, well, this is what I thought but the result was surprising to me, the classes that have static constructors take much more time to be accessed than those that don't have static constructors (see the results at the end of this post). My wild guess is that every time a class with a static constructor is accessed the runtime checks whether the static constructor was called or not which causes the performance hit. Without further ado, here's the code below and the results of running the test on my computer .

More details:

I used the release build in the test (not the debug build as it very often gives very wrong results)
Software used in the test:

• Windows XP Pro SP2
• .NET Framework 2.0

The specs of my computer (where the test was done) are:

• CPU Intel 1.6GHz Dual Core
• 1024 MB RAM

Used Code

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;

namespace singleton_vs_nested_classes
{
    class Program
    {
        static void Main(string[] args)
        {
            const int LOOP_COUNT = 1000000000;
            int tempVar = 0;
            Thread.Sleep(3000);

            // TestStatic
            //
            tempVar = TestStatic.TestVar;
            DateTime beforeTestStatic = DateTime.Now;
            for (int i = 0; i < LOOP_COUNT; i++)
            {
                tempVar = TestStatic.TestVar;
            }
            DateTime afterTestStatic = DateTime.Now;

            // TestStaticWithTypeInitializer
            //
            tempVar = TestStaticWithTypeInitializer.TestVar;
            DateTime beforeTestStaticWithTypeInitializer = DateTime.Now;
            for (int i = 0; i < LOOP_COUNT; i++)
            {
                tempVar = TestStaticWithTypeInitializer.TestVar;
            }
            DateTime afterTestStaticWithTypeInitializer = DateTime.Now;

            // TestNested
            //
            tempVar = TestNested.MyNestedClass.TestVar;
            DateTime beforeTestNested = DateTime.Now;
            for (int i = 0; i < LOOP_COUNT; i++)
            {
                tempVar = TestNested.MyNestedClass.TestVar;
            }
            DateTime afterTestNested = DateTime.Now;

            // TestSingltonLazyLoading
            //
            tempVar = TestSingltonLazyLoading.Singlton.TestVar;
            DateTime beforeTestSingltonLazyLoading = DateTime.Now;
            for (int i = 0; i < LOOP_COUNT; i++)
            {
                tempVar = TestSingltonLazyLoading.Singlton.TestVar;
            }
            DateTime afterTestSingltonLazyLoading = DateTime.Now;

            // TestSingltonInitInTypeInitliazer
            //
            tempVar = TestSingltonInitInTypeInitliazer.Singlton.TestVar;
            DateTime beforeTestSingltonInitInTypeInitliazer = DateTime.Now;
            for (int i = 0; i < LOOP_COUNT; i++)
            {
                tempVar = TestSingltonInitInTypeInitliazer.Singlton.TestVar;
            }
            DateTime afterTestSingltonInitInTypeInitliazer = DateTime.Now;

            // Show results
            //
            Console.WriteLine("{0} TestStatic", afterTestStatic.Subtract(beforeTestStatic));
            Console.WriteLine("{0} TestStaticWithTypeInitializer", afterTestStaticWithTypeInitializer.Subtract(beforeTestStaticWithTypeInitializer));
            Console.WriteLine("{0} TestNested", afterTestNested.Subtract(beforeTestNested));
            Console.WriteLine("{0} TestSingltonLazyLoading", afterTestSingltonLazyLoading.Subtract(beforeTestSingltonLazyLoading));
            Console.WriteLine("{0} TestSingltonInitInTypeInitliazer", afterTestSingltonInitInTypeInitliazer.Subtract(beforeTestSingltonInitInTypeInitliazer));
            Console.Read();
        }
    }

    public static class TestStatic
    {
        private static int _testVar = 5;
        public static int TestVar
        {
            get
            {
                return _testVar;
            }
        }
    }

    public static class TestStaticWithTypeInitializer
    {
        static TestStaticWithTypeInitializer()
        {
            _testVar = 5;
        }

        private static int _testVar;
        public static int TestVar
        {
            get
            {
                return _testVar;
            }
        }
    }

    public static class TestNested
    {
        public static class MyNestedClass
        {
            private static int _testVar = 5;
            public static int TestVar
            {
                get
                {
                    return _testVar;
                }
            }
        }
    }

    public static class TestSingltonLazyLoading
    {
        private static TestSinglton _singltonInstance;
        public static TestSinglton Singlton
        {
            get
            {
                if (_singltonInstance == null)
                {
                    _singltonInstance = new TestSinglton(5);
                }
                return _singltonInstance;
            }
        }
    }

    public static class TestSingltonInitInTypeInitliazer
    {
        static TestSingltonInitInTypeInitliazer()
        {
            _singltonInstance = new TestSinglton(5);
        }

        private static TestSinglton _singltonInstance;
        public static TestSinglton Singlton
        {
            get
            {
                return _singltonInstance;
            }
        }
    }

    public class TestSinglton
    {
        public TestSinglton(int testVar)
        {
            _testVar = testVar;
        }

        private int _testVar;
        public int TestVar
        {
            get
            {
                return _testVar;
            }
        }
    }
}

Results: 00:00:01.2656250 TestStatic
00:00:12.8437500 TestStaticWithTypeInitializer
00:00:01.2812500 TestNested
00:00:03.2187500 TestSingltonLazyLoading
00:00:09.3125000 TestSingltonInitInTypeInitliazer