I have this C# method which I'm trying to optimize:

// assume arrays are same dimensions
private void DoSomething(int[] bigArray1, int[] bigArray2)
{
    int data1;
    byte A1;
    byte B1;
    byte C1;
    byte D1;
    int data2;
    byte A2;
    byte B2;
    byte C2;
    byte D2;
    for (int i = 0; i < bigArray1.Length; i++)
    {
        data1 = bigArray1[i];
        data2 = bigArray2[i];

        A1 = (byte)(data1 >> 0);
        B1 = (byte)(data1 >> 8);
        C1 = (byte)(data1 >> 16);
        D1 = (byte)(data1 >> 24);

        A2 = (byte)(data2 >> 0);
        B2 = (byte)(data2 >> 8);
        C2 = (byte)(data2 >> 16);
        D2 = (byte)(data2 >> 24);

        A1 = A1 > A2 ? A1 : A2;
        B1 = B1 > B2 ? B1 : B2;
        C1 = C1 > C2 ? C1 : C2;
        D1 = D1 > D2 ? D1 : D2;

        bigArray1[i] = (A1 << 0) | (B1 << 8) | (C1 << 16) | (D1 << 24); 
    }
}

The function basically compares two int arrays. For each pair of matching elements, the method compares each individual byte value and takes the larger of the two. The element in the first array is then assigned a new int value constructed from the 4 largest byte values (irrespective of source).

I think I have optimized this method as much as possible in C# (probably I haven't, of course - suggestions on that score are welcome as well). My question is, is it worth it for me to move this method to an unmanaged C DLL? Would the resulting method execute faster (and how much faster), taking into account the overhead of marshalling my managed int arrays so they can be passed to the method?

If doing this would get me, say, a 10% speed improvement, then it would not be worth my time for sure. If it was 2 or 3 times faster, then I would probably have to do it.

Note: please, no "premature optimization" comments, thanks in advance. This is simply "optimization".