Normalization vs denormalization

Normalized databases fair very well under conditions where the applications are write-intensive and the write-load is more than the read-load. 
Denormalized databases fair well under heavy read-load and when the application is read intensive. 

 normalization eliminates the data redundancy within a table, which greatly reduces the risk that data may become inconsistent.

In a relational database, denormalization is an approach to optimizing performance in which the administrator selectively adds back specific instances of duplicate data after the data structure has been normalized.

However, when denormalizing the schema, do take into consideration, the number of times you would be updating records compared to the number of times you would be executing SELECTs. When mixing normalization and denormalization, focus on denormalizing tables that are read intensive, while tables that are write intensive keep them normalized.