Denormalization of dimension tables in InfoCube in SAP BW

Note that In Data Warehouse, data load is less frequent as compared to data read. If you use normalized tables that result more number of joins and hence when you run multiple read statements on DW system, it effects the performance considerably.

When you are not using normalized tables, the response time of queries are improved however load time and memory space is increased.

You can refer below link to get advantages of denormalization in database and comparison with normalized tables.

http://searchdatamanagement.techtarget.com/definition/denormalization