✅ Which of these for-loops is more performant? How can I improve

public class Solution {
    public int[] DecodeOne(int[] encoded, int first)
    {
        var arr = new int[encoded.Length + 1];
        arr[0] = first;
        
        for (int i = 1; i < arr.Length; i++)
        {
            arr[i] = encoded[i-1]^arr[i-1];
        }

        return arr;
    }

    public int[] DecodeTwo(int[] encoded, int first)
    {
        var intSize = sizeof(int);
        var arr = new int[encoded.Length + 1];
        arr[0] = first;
        System.Buffer.BlockCopy(encoded, 0, arr, intSize, intSize * encoded.Length);
        
        for (int i = 1; i < arr.Length; i++)
        {
            arr[i] ^= arr[i-1];
        }

        return arr;
    }
}