The pre logon init metric, displayed on the dashboard Single Logon, measures the time from session creation until user logon. High values may or may not indicate a problem, depending on the situation.
Example 1: Citrix XenApp
During a logon to a Citrix XenApp terminalserver typically a new session is created. In this case, the pre logon init metric is important: it shows how long it takes to prepare the new session and connect to it from the client.
Example 1: Physical PC
On a PC, on the other hand, the situation is often different. When a machine is booted, it presents its logon screen, waiting for the user to enter credentials. That, however, may take a very long time. The user might not even be near the machine when it is started. Therefore the pre logon init value can be very high without indicating a problem.