如果在C＃语句的性能

我只是想确定，当它被用在与大量的迭代周期对我的C＃应用​​程序的性能每一个如果声明的影响。我还没有发现关于这个话题，所以我创建了这一点。

I'm just trying to determine the impact of each "if" statement on the performance of my C# application when it is used in cycles with large number of iterations. I have not found the topic about this so I have created this one.

有关测试我做了2个周期：一个没有如果，一个用一个if语句。在code是如下。

For the test I made 2 cycles: one without "if" and one with a single "if" statement. The code is the following.

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

namespace IfPerformance
{
    class Program
    {
        static void Main(string[] args)
        {
            int N = 500000000;
            Stopwatch sw = new Stopwatch();

            double a = 0, b = 0;
            bool f;

            sw.Restart();
            for (int i = 0; i < N; i++)
            {
                a += 1.1;
                f = a < N;
            }
            sw.Stop();
            Console.WriteLine("Without if: " + sw.ElapsedMilliseconds + " ms");

            a = 0;
            sw.Restart();
            for (int i = 0; i < N; i++)
            {
                if (a < N)
                    a += 1.1;
                else
                    b += 1.1;
            }
            sw.Stop();
            Console.WriteLine("With if:    " + sw.ElapsedMilliseconds + " ms");
            Console.ReadKey();
        }
    }
}

我跑了试验用优化code构建选项和不开始调试。结果如下： 如果没有的话：154毫秒 随着如果：742毫秒

I ran the test with "Optimize code" build option and "Start without debugging". The result is the following: Without if: 154 ms With if: 742 ms

这意味着一个if语句带来近5倍增长放缓的表现。我觉得这方面会有所帮助。

This means that a single "if" statement brings almost 5 times slowdown to the performance. I think regarding this will be helpful.

另外，我注意到的presence一些额外的if在一个大的循环可能由25％，这在我看来是显著减慢我的最终应用。

Also, I have noticed that the presence of several extra "if"s in a large loop may slow down my final application by 25%, which on my opinion is significant.

要具体，我在一组数据，需要通过整个数据集多回路的运行蒙特卡洛优化。该循环包含分支这取决于用户的设置。从这个角度的if出现。

To be specific, I'm running Monte-Carlo optimization on a set of data, which require many loops through the whole data set. The loop contains branching which depends on the user settings. From this point "if"s arise.

我的问题在性能方面的专业人士：

My questions to the professionals in performance aspects are:

1. 什么是额外的if上运行多个迭代的时间的影响，在一个循环？
2. 如何避免衰退？

请发表您的意见，如果我去了错误的方向。

Please post your opinion if I'm going in the wrong direction.