From the Performance Explorer right click an Activity and select either Compare with baseline or Compare with previous.

Another way to compare Activities is to select two activities in the Performance Explorer, right click, then select Compare.

The Hotspots Comparison Browser is used to compare the performance of the application between two Activities. This is useful to determine how a change has affected the application's performance.
At the top of the browser the overall performance change is stated.

The table lists the functions that have had the largest impact on the change to the application's performance.
The runtime behaviour of the application can be effected by certain environment variables set on the system. An extra panel will be available if changes to these environment variables are detected. Click the small arrow to expand the panel, this will display a table that shows the name of each environment variable and its value in each run. For a list of the relevant environment variables please refer to the page on environment variables for performance tuning.
