Is it better to only make searchable indexes available via the Selected search indexes option rather than using Restrict search terms?

[jaho_splunk]

If I leave the Restrict search terms option empty and only make searchable indexes available via the Selected search indexes option, is this more efficient than using the Restrict search terms option to name the indexes they may search? If the client is allowed to search the entire index, leaving Restrict search terms empty does not negatively affect their search / search time does it?

[martin_mueller]

If you want to restrict a user to a set of indexes, use srchIndexesAllowed.
If you have to restrict a user based on other criteria, use srchFilter.
http://docs.splunk.com/Documentation/Splunk/6.4.0/Admin/authorizeconf#.5Brole_.3CroleName.3E.5D

The performance of srchFilter = index=foo will be fine, but it's really ugly and pointless.