There are many factors contributing to the time it takes for an audit to complete, including:
Page load time The ObservePoint engine loads each page of the audit in a browser. The faster a page loads, the faster the audit completes.
Simultaneous connections Adobe Auditor uses a single connection to visit each page. Full ObservePoint accounts use as many as 10 engines at once.
Network silence After each page loads, the audit waits for a network silence of seven seconds before proceeding to the next page. If a page sends a lot of network requests that occur after the page loads, the wait will timeout after 60 seconds.
Page Retries If a page or tag cannot be found, the audit stores that URL and returns to it later in the audit. The audit will visit a page up to three times to make sure that the error was not caused by a transient issue.
Processing After an audit has run, all the data it has collected is processed and filtered through the rules. This processing time is significant, though it doesn't take as much time as the scan itself.
Note: Adobe Auditor runs a single scan at a time. Full ObservePoint accounts can run many audits consecutively.