Tuning and Error Search 
With the Web Dynpro Trace Tool you can optimize your applications for Delta Rendering. The trace tool displays which areas of a view have been updated and at the same time lists the reasons for the updates.
Features
The updated area of the view is displayed in a green frame.
The trace tool and its functions are displayed in the lower part of the browser window.
Note
Note that the full page is always updated for the first request.
Example
DEMO_ROADMAP
DeltaRenderingChange Tracking
The entry DeltaRenderingChange Tracking, which appears in the dropdown list after the application is first called, is used to create a trace file DeltaRenderingChangeTracking.xml, in which all changes ocurring in a roundtrip are recorded.
You can either display the changes directly in the GUI or in a separate window, and save as a local file.
Even if only one single change is triggered for a view, the complete view is still updated. In columns PROGRAM, EVENT and LINE you can see exactly where the change was triggered in the program code.
Changes may come from the Web Dynpro application or be triggered by user actions. Each user action, except for focus changes, results in an update of the surrounding view. A user action can result in an update of the context or in changes to view elements. These types of update appear in the trace file under PROGRAMM as <WebDynproFramework>.
Procedure
Activate tracing in the SAP GUI.
In transaction WD_TRACE_TOOL choose the pushbutton Activate for this User. This sets the status of the trace to active for the user in question. Choose OK to confirm the warning relating to the necessary security settings.
Call the application to be traced in the browser and add the URL Parameter sap-wd-DeltaRendering with value ON to the URL.
Choose Enter.
Execute some roundtrips.
In the dropdown list, choose Delta Rendering Change Tracking.
Choose Stop Trace... and save files locally.
Open DeltaRenderingChangeTracking.xml and analyze the data there.