This setting is the maximum number of raw (pre-auth-check) search result URLs to examine for authorized results, during results authorization. Decreasing this limit can speed up searches and reduce origin server load, at the cost of possibly truncated displayed results. E.g. noisy queries that match many overall documents on the server, but few of which are authorized for the search user, may use a lot of server resources, so reducing this limit may reduce that load.
The maximum value is -1 or blank (the default), for no limit: i.e. continue until all results are checked, or Successful Auth Result Limit or Total Auth Timeout is reached.