Complexity of hashes?

Recently I have made various hashes programs in C++, e.g. to convert a name to number for answering queries of the type that if the name exists or not, but the execution time for the programs is too much! Why is that? Is it because it multiplies long long numbers which is slow?

Complexity is O(1). (the complexity of the hash function)

If it is not working ask yourself, what type of hashing are you using? How long are the strings? How many strings are there? How much space to store strings do you have? Is the hash function adequate?

C++10 has unordered_set, maybe you can test it