c#和c++在性能方面有一些主要的区别:

c#是基于GC /堆的。分配和GC本身是内存访问的非局部性开销 多年来，c++优化器已经变得非常好。JIT编译器无法达到相同的级别，因为它们只有有限的编译时间，并且看不到全局作用域

除此之外，程序员的能力也很重要。我见过一些糟糕的c++代码，其中的类通过值作为参数传递。在c++中，如果你不知道自己在做什么，实际上会让性能变差。

快了5个橘子。或者更确切地说:不可能有一个(正确的)笼统的答案。c++是一种静态编译语言(但也有配置文件引导的优化)，c#在JIT编译器的帮助下运行。它们之间的差异如此之大，以至于像“快了多少”这样的问题都无法回答，甚至无法给出数量级。

C/ c++在有大型数组或数组(任何大小)上的大量循环/迭代的程序中可以表现得更好。这就是为什么在C/ c++中图形化通常要快得多，因为几乎所有的图形化操作都基于繁重的数组操作。net在数组索引操作中是出了名的慢，这是由于所有的安全检查，这对于多维数组尤其如此(是的，矩形c#数组甚至比锯齿形c#数组还要慢)。

The bonuses of C/C++ are most pronounced if you stick directly with pointers and avoid Boost, std::vector and other high-level containers, as well as inline every small function possible. Use old-school arrays whenever possible. Yes, you will need more lines of code to accomplish the same thing you did in Java or C# as you avoid high-level containers. If you need a dynamically sized array, you will just need to remember to pair your new T[] with a corresponding delete[] statement (or use std::unique_ptr)—the price for the extra speed is that you must code more carefully. But in exchange, you get to rid yourself of the overhead of managed memory / garbage collector, which can easily be 20% or more of the execution time of heavily object-oriented programs in both Java and .NET, as well as those massive managed memory array indexing costs. C++ apps can also benefit from some nifty compiler switches in certain specific cases.

I am an expert programmer in C, C++, Java, and C#. I recently had the rare occasion to implement the exact same algorithmic program in the latter 3 languages. The program had a lot of math and multi-dimensional array operations. I heavily optimized this in all 3 languages. The results were typical of what I normally see in less rigorous comparisons: Java was about 1.3x faster than C# (most JVMs are more optimized than the CLR), and the C++ raw pointer version came in about 2.1x faster than C#. Note that the C# program only used safe code—it is my opinion that you might as well code it in C++ before using the unsafe keyword.

Lest anyone think I have something against C#, I will close by saying that C# is probably my favorite language. It is the most logical, intuitive and rapid development language I've encountered so far. I do all my prototyping in C#. The C# language has many small, subtle advantages over Java (yes, I know Microsoft had the chance to fix many of Java's shortcomings by entering the game late and arguably copying Java). Toast to Java's Calendar class anyone? If Microsoft ever spends real effort to optimize the CLR and the .NET JITter, C# could seriously take over. I'm honestly surprised they haven't already—they did so many things right in the C# language, why not follow it up with heavy-hitting compiler optimizations? Maybe if we all beg.

对于图形来说，标准的c#图形类比通过C/ c++访问的GDI慢得多。 我知道这与语言本身无关，更多的是与整个。net平台有关，但是图形是作为GDI替代品提供给开发人员的，它的性能非常糟糕，我甚至不敢用它来处理图形。

我们有一个简单的基准来查看图形库的速度，那就是在窗口中随机绘制线条。c++ /GDI在处理10000行代码时仍然很灵活，而c# /Graphics在处理1000行代码时却很难做到。

毕竟，答案总要在某个地方，不是吗?：）

嗯,没有。

正如一些回复所指出的那样，这个问题在某种程度上没有得到充分的说明，只会引起问题的回应，而不是答案。只从一个方面来说:

这个问题将语言和语言实现合并在一起——这个C程序比c#程序慢2194倍，快1.17倍——我们不得不问你:哪种语言实现?

然后是哪些项目?哪个机器?哪些操作系统?哪个数据集?

这要看情况。如果字节码被转换成机器代码(不仅仅是JIT)(我的意思是如果你执行程序)，如果你的程序使用了很多分配/释放，它可能会更快，因为GC算法只需要一次(理论上)通过整个内存，但正常的malloc/realloc/free C/ c++调用会在每次调用上引起开销(调用开销、数据结构开销、缓存丢失;))。

所以这在理论上是可能的(对于其他GC语言也是如此)。

我并不认为不能在大多数应用程序中使用c#元编程有什么极端的缺点，因为大多数程序员都不使用它。

另一个很大的优势是SQL，像LINQ“扩展”一样，为编译器提供了优化数据库调用的机会(换句话说，编译器可以将整个LINQ编译为一个“blob”二进制文件，其中调用的函数内联或为您的使用优化，但我只是在这里推测)。