How to measure the performance of a C# method?

The Stopwatch class in System.Diagnostics namespace provides a set of methods and properties that you can use to accurately measure elapsed time.

The following example uses the Stopwatch class to measure the performance of four different implementations for parsing an integer from a string.

using System.Diagnostics;

public static void TestIntParse(int operation)
{
    long ticksThisTime = 0;
    int inputNum;
    Stopwatch timePerParse;
    string desc = string.Empty;

    switch (operation)
    {
        case 0:
            // Parse a valid integer using
            // a try-catch statement.

            desc = "Int32.Parse(\"0\")";

            // Start a new stopwatch timer.
            timePerParse = Stopwatch.StartNew();

            try
            {
                inputNum = Int32.Parse("0");
            }
            catch (FormatException)
            {
                inputNum = 0;
            }

            // Stop the timer, and save the
            // elapsed ticks for the operation.

            timePerParse.Stop();
            ticksThisTime = timePerParse.ElapsedTicks;
            break;
        case 1:
            // Parse a valid integer using
            // the TryParse statement.

            desc = "Int32.TryParse(\"0\" out input)";

            // Start a new stopwatch timer.
            timePerParse = Stopwatch.StartNew();

            if (!Int32.TryParse("0", out inputNum))
            {
                inputNum = 0;
            }

            // Stop the timer, and save the
            // elapsed ticks for the operation.
            timePerParse.Stop();
            ticksThisTime = timePerParse.ElapsedTicks;
            break;
        case 2:
            // Parse an invalid value using
            // a try-catch statement.

            desc = "Int32.Parse(\"a\")";

            // Start a new stopwatch timer.
            timePerParse = Stopwatch.StartNew();

            try
            {
                inputNum = Int32.Parse("a");
            }
            catch (FormatException)
            {
                inputNum = 0;
            }

            // Stop the timer, and save the
            // elapsed ticks for the operation.
            timePerParse.Stop();
            ticksThisTime = timePerParse.ElapsedTicks;
            break;
        case 3:
            // Parse an invalid value using
            // the TryParse statement.

             desc = "Int32.TryParse(\"a\" out input)";

            // Start a new stopwatch timer.
            timePerParse = Stopwatch.StartNew();

            if (!Int32.TryParse("a", out inputNum))
            {
                inputNum = 0;
            }

            // Stop the timer, and save the
            // elapsed ticks for the operation.
            timePerParse.Stop();
            ticksThisTime = timePerParse.ElapsedTicks;
            break;

        default:
            break;
    }

    double ms = (ticksThisTime * 1000.0) / Stopwatch.Frequency;

    Console.WriteLine(string.Format("{0} spents {1} milliseconds.", desc, ms));
}

public static void Main()
{
    TestIntParse(0);
    TestIntParse(1);
    TestIntParse(2);
    TestIntParse(3);
}

The output for above exampe would be:

Int32.Parse("0") spents 0.019834923153641 milliseconds.

Int32.TryParse("0" out input) spents 0.0170412720052409 milliseconds.

Int32.Parse("a") spents 55.8685531261655 milliseconds.

Int32.TryParse("a" out input) spents 0.0117333348232806 milliseconds.