Boosting C# Array Concatenation Performance: A Superior Alternative to Concat

C#'s Concat method provides a simple solution for joining arrays. However, its performance can be suboptimal when dealing with large arrays. For significantly improved efficiency in array concatenation, consider this alternative:

int[] x = new int[] { 1, 2, 3 };
int[] y = new int[] { 4, 5 };

int[] z = new int[x.Length   y.Length];
Array.Copy(x, z, x.Length);
Array.Copy(y, 0, z, x.Length, y.Length);

Debug.Assert(z.SequenceEqual(new int[] { 1, 2, 3, 4, 5 }));

This method directly allocates a new array z of sufficient size to hold both x and y. It then leverages Array.Copy to efficiently transfer the elements of x and y into z. This avoids the creation of intermediate arrays, leading to faster execution, especially with larger datasets.

Important Consideration: While Concat remains suitable for smaller arrays where performance isn't critical, the approach above offers a substantial performance advantage for scenarios involving large arrays.