C++复制内存比C#稍快

[TestMethod]
    public void MemcpyUseTime()
    {
        byte[] src = Enumerable.Repeat((byte)0x08, 1000*1000*10).ToArray();
        src[0] = 5;
        src[10000] = 6;
        IntPtr ptr = Marshal.AllocHGlobal(src.Length);
        for (int i = 0; i < 5000; i++)
        {
            Marshal.Copy(src, 0, ptr, src.Length);
        }
        unsafe { 
        byte* pb = (byte*)ptr;
        Assert.AreEqual(5, pb[0]);
        Assert.AreEqual(6, pb[10000]);
        }
    }
TEST_METHOD(TestMethod1)
        {
            const int iNum = 1000 * 1000 * 10;
            char* p = new char[iNum];
            memset(p, iNum, 0);
            p[0] = 5;
            p[10000] = 6;
            char* p2 = new char[iNum];
            for (int i = 0; i < 5000; i++)
            {
                memcpy(p2, p, iNum);
            }
            Assert::AreEqual((char)5 , p2[0]);
            Assert::AreEqual((char)6, p2[10000]);
        }