c# – 如何提高这个算法的性能？

test.in文件与文字：

> 1行 – 所有字频对的总计数
> 2行??100 001 – 字频对
> 100 002行 – 用户输入字的总数
>从100 003到最终用户输入字

我解析这个文件并把这些单词放进去

Dictionary<string,double> dictionary;

我想在以下代码中执行一些搜索顺序逻辑：

for(int i=0;i<15000;i++)
{
    tempInputWord = //take data from file(or other sources)

    var adviceWords = dictionary
                .Where(p => p.Key.StartsWith(searchWord,StringComparison.Ordinal))
                .OrderByDescending(ks => ks.Value)
                .ThenBy(ks => ks.Key,StringComparer.Ordinal)
                .Take(10)
                .ToList();

    //some output
}

问题：该代码必须在不到10秒的时间内运行.

在我的电脑(核心i5 2400,8gb RAM)与Parallel.For() – 约91秒.

你能给我一些如何提高性能的建议吗？

更新：

万岁！我们做到了！
谢谢@CodesInChaos,@usr,@T_D和所有参与解决问题的人.

最后的代码：

var kvList = dictionary.OrderBy(ks => ks.Key,StringComparer.Ordinal).ToList();

var strComparer = new MyStringComparer();
var intComparer = new MyIntComparer();
var kvListSize = kvList.Count;
var allUserWords = new List<string>();
for (int i = 0; i < userWordQuantity; i++)
{
    var searchWord = Console.ReadLine();
    allUserWords.Add(searchWord);
}
var result =  allUserWords
    .AsParallel()
    .AsOrdered()
    .Select(searchWord =>
    {
        int startIndex = kvList.BinarySearch(new KeyValuePair<string,int>(searchWord,0),strComparer);
        if (startIndex < 0)
            startIndex = ~startIndex;

        var matches = new List<KeyValuePair<string,int>>();

        bool isNotEnd = true;
        for (int j = startIndex; j < kvListSize ; j++)
        {
            isNotEnd = kvList[j].Key.StartsWith(searchWord,StringComparison.Ordinal);
            if (isNotEnd) matches.Add(kvList[j]);
            else break;
        }
        matches.Sort(intComparer);

        var res = matches.Select(s => s.Key).Take(10).ToList();

        return res;
    });
foreach (var adviceWords in result)
{
   foreach (var adviceWord in adviceWords)
   {
       Console.WriteLine(adviceWord);
   }
   Console.WriteLine();
}

6 sec (9 sec without manual loop (with linq)))