我发现2020年4月读过:https://www.quora.com/Why-is-C-so-slow-compared-to-Python，作者是一位拥有15年以上软件开发经验的现实世界的程序员。

它指出，c#通常较慢，因为它被编译为公共中间语言(CIL)，而不是像c++那样的机器代码。然后，CIL通过公共语言运行库(CLR)输出机器代码。但是，如果您继续执行c#，它将获取机器代码的输出并缓存它，以便为下次执行保存机器代码。总而言之，如果多次执行，c#会更快，因为它是多次执行后的机器代码。

也有评论说，一个优秀的c++程序员可以做一些耗时的优化，但最终会被优化。

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)。

据我所知…

你的困难似乎在于决定你所听到的是否可信，当你试图评估这个网站上的回复时，这个困难将会重复。

你将如何判断人们在这里所说的比你最初听到的更可信还是更不可信?

一种方法是要求提供证据。

当有人声称“在某些领域c#被证明比c++快”时，问他们为什么这么说，让他们给你看测量结果，让他们给你看程序。有时他们只是犯了一个错误。有时你会发现他们只是在表达一种观点，而不是分享一些他们可以证明是正确的事情。

通常情况下，信息和观点会混淆在人们的说法中，你必须试着分清哪个是哪个。例如，从这个论坛的回复中:

"Take the benchmarks at http://shootout.alioth.debian.org/ with a great deal of scepticism, as these largely test arithmetic code, which is most likely not similar to your code at all." Ask yourself if you really understand what "these largely test arithmetic code" means, and then ask yourself if the author has actually shown you that his claim is true. "That's a rather useless test, since it really depends on how well the individual programs have been optimized; I've managed to speed up some of them by 4-6 times or more, making it clear that the comparison between unoptimized programs is rather silly." Ask yourself whether the author has actually shown you that he's managed to "speed up some of them by 4-6 times or more" - it's an easy claim to make!

. net语言可以像c++代码一样快，甚至更快，但是c++代码将拥有更恒定的吞吐量，因为. net运行时必须暂停进行GC，即使它非常巧妙地处理了暂停。

因此，如果您有一些代码必须持续快速运行而不需要任何暂停，. net在某些时候会引入延迟，即使您非常小心地使用运行时GC。

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.