Is it better to have a HashMap with large number of records or n number of small hashMaps?

It depends on the different scenario one is working on:
1) If the objects in the hashMap are same then there is no point in having different hashmap as the traverse time in a hashmap is invariant to the size of the Map.
2) If the objects are of different type like one of Person class , other of Animal class etc then also one can have single hashmap but different hashmap would score over it as it would have better readability.