A dashboard is taking too long to load.

 The correct answer is B and D, because they are the ways to optimize the searches in the dashboard. A dashboard is a user interface that displays data from one or more searches in various panels, such as charts, tables, or maps. Optimizing the searches in the dashboard helps to improve the dashboard performance, reduce the load on the Splunk server, and enhance the user experience. Restricting the time range of the search as much as possible and converting the common SPL into a Global Search and converting the other searches to post-processing searches are both methods to optimize the searches in the dashboard by limiting the amount of data to be searched or processed. Converting searches to include NOT expressions and replacing | stats command with | transaction command wherever possible are not methods to optimize the searches in the dashboard, but rather ways to change the search logic or functionality, which might not produce the desired results.