For performance enhancement, you can specify some values for the distribute data (DSTDTA) parameter.
One way to ensure the best performance is to specify *BUFFERED for the DSTDTA parameter on the Override with Database File (OVRDBF) command. This tells the system to retrieve data from a distributed file as quickly as possible, potentially even at the expense of immediate updates that are to be made to the file. DSTDTA(*BUFFERED) is the default value for the parameter when a file is opened for read-only purposes.
The other values for the DSTDTA parameter are *CURRENT and *PROTECTED. *CURRENT allows updates by other users to be made to the file, but at some expense to performance. When a file is opened for update, DSTDTA(*CURRENT) is the default value. *PROTECTED gives performance that is similar to that of *CURRENT, but *PROTECTED prevents updates from being made by other users while the file is open.