Use RowsetSize property to set the size of a single rows set, that will be fetched at a single fetch operation. To change RowsetSize for already used dataset, application may call Disconnect method first. 

AnyDAC uses underlying DBMS CLI features to optimize the result set fetching. Most of the supported DBMS's offers row set fetching feature, while MySQL Server, Microsoft Access database does not. The row set fetching allows to transfer few records from a DBMS server to a DBMS client in a single packet at single round trip. That raises the fetching performance few times, comparing to fetching by one record per fetch operation and transmitting single record per round trip. 

If DBMS does not support row set fetching, then AnyDAC will emulate it, unifying fetching behavior across all drivers. 

There is significant performance difference between RowsetSize <= 5 and RowsetSize >= 50. But there may be no significant performance difference between RowsetSize ~= 100 and RowsetSize ~= 500, for example. Anyway, you should check what value will be more suitable for your environment.

property RowsetSize: Integer;

Fetching Rows, Mode, Unidirectional