This is again a typical collection.NET interview question. Dictionary is faster than hashtable as dictionary is a generic strong type. Hashtable is slower as it takes object as data type which leads to boxing and unboxing.

Below goes the same code for hashtable and dictionary.
 

Hashtable hashtable = new Hashtable();
hashtable[1] = "One";
hashtable[2] = "Two";
hashtable[13] = "Thirteen";

var dictionary = new Dictionary<string, int>();
dictionary.Add(i.ToString("00000"), 10);
dictionary.Add(i.ToString("00000"), 11);

 
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