使用Buffer.BlockCopy。它的全部目的是快速执行（参见Buffer）：
与 System.Array 类中的类似方法相比，此类在操作原始类型方面提供了更好的性能。
诚然，我没有做过任何基准测试，但这就是文档。它也适用于多维数组；只需确保您始终指定要复制多少 字节，而不是多少元素，并且您正在处理原始数组。
此外，我还没有对此进行测试，但是如果您将委托绑定到 System.Buffer.memcpyimpl 并直接调用它，您可能能够从系统中挤出更多性能。签名是：
internal static unsafe void memcpyimpl(byte* src, byte* dest, int len)
它确实需要指针，但我相信它已针对可能的最高速度进行了优化，因此我认为没有任何方法可以比这更快，即使您手头有组装。
更新：
由于请求（并满足我的好奇心），我对此进行了测试：
using System;
using System.Diagnostics;
using System.Reflection;
unsafe delegate void MemCpyImpl(byte* src, byte* dest, int len);
static class Temp
{
//There really should be a generic CreateDelegate<T>() method... -___-
static MemCpyImpl memcpyimpl = (MemCpyImpl)Delegate.CreateDelegate(
typeof(MemCpyImpl), typeof(Buffer).GetMethod("memcpyimpl",
BindingFlags.Static | BindingFlags.NonPublic));
const int COUNT = 32, SIZE = 32 << 20;
//Use different buffers to help avoid CPU cache effects
static byte[]
aSource = new byte[SIZE], aTarget = new byte[SIZE],
bSource = new byte[SIZE], bTarget = new byte[SIZE],
cSource = new byte[SIZE], cTarget = new byte[SIZE];
static unsafe void TestUnsafe()
{
Stopwatch sw = Stopwatch.StartNew();
fixed (byte* pSrc = aSource)
fixed (byte* pDest = aTarget)
for (int i = 0; i < COUNT; i++)
memcpyimpl(pSrc, pDest, SIZE);
sw.Stop();
Console.WriteLine("Buffer.memcpyimpl: {0:N0} ticks", sw.ElapsedTicks);
}
static void TestBlockCopy()
{
Stopwatch sw = Stopwatch.StartNew();
sw.Start();
for (int i = 0; i < COUNT; i++)
Buffer.BlockCopy(bSource, 0, bTarget, 0, SIZE);
sw.Stop();
Console.WriteLine("Buffer.BlockCopy: {0:N0} ticks",
sw.ElapsedTicks);
}
static void TestArrayCopy()
{
Stopwatch sw = Stopwatch.StartNew();
sw.Start();
for (int i = 0; i < COUNT; i++)
Array.Copy(cSource, 0, cTarget, 0, SIZE);
sw.Stop();
Console.WriteLine("Array.Copy: {0:N0} ticks", sw.ElapsedTicks);
}
static void Main(string[] args)
{
for (int i = 0; i < 10; i++)
{
TestArrayCopy();
TestBlockCopy();
TestUnsafe();
Console.WriteLine();
}
}
}
结果：
Buffer.BlockCopy: 469,151 ticks
Array.Copy: 469,972 ticks
Buffer.memcpyimpl: 496,541 ticks
Buffer.BlockCopy: 421,011 ticks
Array.Copy: 430,694 ticks
Buffer.memcpyimpl: 410,933 ticks
Buffer.BlockCopy: 425,112 ticks
Array.Copy: 420,839 ticks
Buffer.memcpyimpl: 411,520 ticks
Buffer.BlockCopy: 424,329 ticks
Array.Copy: 420,288 ticks
Buffer.memcpyimpl: 405,598 ticks
Buffer.BlockCopy: 422,410 ticks
Array.Copy: 427,826 ticks
Buffer.memcpyimpl: 414,394 ticks
现在改变顺序：
Array.Copy: 419,750 ticks
Buffer.memcpyimpl: 408,919 ticks
Buffer.BlockCopy: 419,774 ticks
Array.Copy: 430,529 ticks
Buffer.memcpyimpl: 412,148 ticks
Buffer.BlockCopy: 424,900 ticks
Array.Copy: 424,706 ticks
Buffer.memcpyimpl: 427,861 ticks
Buffer.BlockCopy: 421,929 ticks
Array.Copy: 420,556 ticks
Buffer.memcpyimpl: 421,541 ticks
Buffer.BlockCopy: 436,430 ticks
Array.Copy: 435,297 ticks
Buffer.memcpyimpl: 432,505 ticks
Buffer.BlockCopy: 441,493 ticks
现在再次更改顺序：
Buffer.memcpyimpl: 430,874 ticks
Buffer.BlockCopy: 429,730 ticks
Array.Copy: 432,746 ticks
Buffer.memcpyimpl: 415,943 ticks
Buffer.BlockCopy: 423,809 ticks
Array.Copy: 428,703 ticks
Buffer.memcpyimpl: 421,270 ticks
Buffer.BlockCopy: 428,262 ticks
Array.Copy: 434,940 ticks
Buffer.memcpyimpl: 423,506 ticks
Buffer.BlockCopy: 427,220 ticks
Array.Copy: 431,606 ticks
Buffer.memcpyimpl: 422,900 ticks
Buffer.BlockCopy: 439,280 ticks
Array.Copy: 432,649 ticks
或者，换句话说：他们非常有竞争力；一般来说，memcpyimpl 最快，但不一定值得担心。