Extracts can be optimized for even better performance results. To optimize an extract, simply right-click on a data source and select Data > Extract > Optimize, as seen in the following screenshot:
Optimization accelerates performance by materializing calculated fields when possible. This means that Tableau actually generates values for calculated fields in the extract so that those values can be looked up instead of calculated. Note that not all calculated fields are materialized. Fields that are not materialized include table calculations, changeable or unstable functions, such as NOW() and TODAY(), and calculated fields using parameters.
When an extract is first created, it is automatically optimized. In other words, calculated fields are automatically materialized when possible. However, over the course of time, calculated fields may be altered that...
