I want to gain some data support about using normalized database is better than denormalized database because another development team suggest to break down some large tables into so many smaller tables, they think that can speed up the performance of database. But, I don't agree with them. Therefore, there involve some many arguments, such transaction time, query time, and so on.
Do you have any research result or data that can prove which database design is better? What's the best database design methodologies if these databases are distributed in three or more locations and they will replicated frequently?