ASP.NET中很多地方用了HybridDictionary。我也是第一次知道HybridDictionary。MSDN上是这么说的：
This class is recommended for cases where the number of elements in a dictionary is unknown. It takes advantage of the improved performance of a ListDictionary with small collections, and offers the flexibility of switching to a Hashtable which handles larger collections better than ListDictionary。
写了个程序测试了下，感觉的确如此，在数量小于10个的时候速度比hashtable快，有时快两倍多。我把字符串作为键，如果字串越长，效果越明显。当数量较多的时候速度反而不如hashtable。
This class is recommended for cases where the number of elements in a dictionary is unknown. It takes advantage of the improved performance of a ListDictionary with small collections, and offers the flexibility of switching to a Hashtable which handles larger collections better than ListDictionary。
写了个程序测试了下，感觉的确如此，在数量小于10个的时候速度比hashtable快，有时快两倍多。我把字符串作为键，如果字串越长，效果越明显。当数量较多的时候速度反而不如hashtable。
