What does it mean? What do I do about it?
-prefetchNumRecs specifies the maximum number of records that can sent in a ""query"" message. Larger values are much more efficient.
Set -prefetchNumRecs 10000.
This may seem excessively high but if you use FIELDS in your FOR EACH logic record sizes can be quite small and a large number of records can be returned in a message.
See also Got remote clients? Use PreFetch!