Evaluate whether or not database parameters are impacting performance.
There are certain database parameters that can impact performance. In particular, you should review the memory related parameters (MEMORY_TARGET, SGA_TARGET, PGA_AGGREGATE_TARGET, SHARED_POOL_SIZE) parameters to ensure they are sized correctly. If you are using the Embedded PL/SQL Gateway, you should make sure that SHARED_SERVERS is sized correctly, to improve performance for multiple concurrent requests.You should also check that the database System Global Area (SGA) fits in real memory. An undersized SGA can dramatically impact Application Express performance. There needs to be sufficient memory in the Shared Pool for PL/SQL and in Buffer Cache for the Application Express metadata. If the SGA is sized correctly it should not be necessary to pin PL/SQL programs from the Application Express engine as they are accessed regularly and should not be swapped out of memory. Because the Application Express engine resides in the database, it is strongly recommended that you gather statistics on the apex_180100 schema. Accurate statistics allow the cost-based optimizer to develop better query plans for accessing the application metadata.
Parent topic: Managing Application Performance