用并行c#将一个矩阵乘以一个标量向量

我有两个数组字典，它们乘在一起并存储在string和int[]的字典中。代码工作

public class Program
{
    public static void Main(string[] args)
    {
        int[] a = {1,0,3,4,0};
        int[] b = { 3, 0, 9, 10, 0};
        int[] c = {2,3,3,5,0};
        var ret = new Dictionary<string, int[]>();
        ret.Add("Jack", a);
        ret.Add("Jane", b);
        ret.Add("James", c);
        var multipliers = new Dictionary<string, int>();
        multipliers.Add("Jack", 2);
        multipliers.Add("Jane", 3);
        multipliers.Add("James", 5);
        var results = new Dictionary<string, int[]>();
        foreach (var item in ret)
        {
            int[] arr= new int[item.Value.Length];
            for (int i = 0; i < item.Value.Length; i ++)
            {
                int d = item.Value[i] * multipliers[item.Key];
                arr[i] = d;
            }
            results.Add(item.Key,arr);
        }
    }
}

做这件事最有效的方法是什么?是否有一种方法可以并行地做到这一点?

var results = new ConcurrentDictionary<string, int[]>();
Parallel.ForEach(ret, pair =>
{
      var srcArr = pair.Value;
      var arr = new int[srcArr.Length];
      var multBy = multipliers[pair.Key];
      for (var i = 0; i < srcArr.Length; i++)
      {
           var d = srcArr[i] * multBy;
           arr[i] = d;
      }
      results[pair.Key] = arr;
});