An application repeatedly accesses small lookup tables, causing a lot of physical I/O operations. What do you recommend to minimize this?

Configuring a nonstandard buffer cache without specifying that the tables should use it does not guarantee these specific tables will remain in memory and not be aged out by other data.

Increasing the size of the shared pool primarily benefits caching of SQL statements, PL/SQL code, and data dictionary information, not directly the data blocks of tables.

The KEEP buffer cache is specifically designed to retain frequently accessed objects, such as small lookup tables, in the buffer cache indefinitely, preventing them from being aged out by the LRU algorithm. By allocating a separate KEEP cache and marking these tables for its use, physical I/O operations for these hot objects are significantly reduced or eliminated.

The RECYCLE buffer cache is intended for objects that are accessed infrequently or for very large objects whose blocks should be aged out quickly to avoid consuming too much buffer cache space, which is the opposite goal for hot lookup tables.