Replicating folders or search results as a whole is faster. A single briefcase is created for all of them (assuming you're setting Replicate Entries to use the results set, not running it in a For Each Entry loop). Briefcasing each file will be slower since each briefcase export/import has to make a tear down a connection to LF repositories. If disk space is a concern, limit the number of search results to more manageable numbers and run the workflow on a schedule.