Which type of persistence should be selected for a Qlik Sense single-node environment?

An Active Directory (AD) contains a large number of objects. To prevent performance issues, the system administrator needs to limit the synchronization of users and groups. The administrator has an existing user directory connector (UDC).
Which is the most efficient approach for the administrator to limit the synch?

A system administrator receives from a user an application made on Qlik Sense Desktop and requests that it be made available to all users. The system administrator imports the QVF file, but the data reload fails.
The system administrator then analyzes the application within Qlik Sense Desktop and realizes that there are script implementations with Section Access.
What exactly is causing problem in reloading on the server?

What is the primary purpose of Section Access in Qlik Sense?

A system administrator notices that several Qlik Sense apps are experiencing performance issues.
What is the best tool to use for identifying resource bottlenecks in the system?