optimize this function to use the fastest enumerable in C# and the function will only get string enumerable so change the T with it 

"
    public static string ListToString<T>(this List<T>? list, char delimiter = ',')
    {
        if (list == null) return "";
        StringBuilder sb = new();
        for (int i = 0; i < list.Count; i++)
        {
            sb.Append(list[i]!.ToString()) ;
            if (i < list.Count - 1) sb.Append(delimiter);
        }
        return sb.ToString();
    }
"
this function is too slow make it fast