Context Filter 

You can enhance efficiency by setting context filters when you apply filters to a big information source. A context filter is used first for the information source and only for the resulting documents are used the other filters. This sequence prevents each filter from being applied to each information source record. 

A context filter may be created to- Performance enhancement. If you set many filters or have a big information source, the query may be slow. To enhance efficiency, you can set ONE or more context filters.  

Create a numerical or N-top dependent filter–a context filter can only be set to include interesting information and then a numeric or N-top filter can be set.

Dual axis 

Multiple steps can be compared using dual axes, two separate axes laid up on top of each other. When two measures are measured in distinct SCALES, double axes are HELPFUL. For instance, the following PERSPECTIVE displays Dow Jones and NASDAQ closing time values. Drag the field to the right of the perspective and drop it if you see a BLACK dashed line to add the measurement as a two-axis. In the field menu, you can also pick the Dual Axis.

The two axes are separate but the layout of the marks is the same.