normalization

Question

In an interview i was asked this question by an interviewer and i can't answer this question, plz reply me the answer.


The question is,


                   I had a table containg some rows and i divided it into 2 or more tables using normalization. Now which gives better performance a single table or a normalization tables. I said normalization tables give better performance. He asked me to give an example but i couldnt.

Plz give me an example with clear explanation.

Thanku.