* In-memory undo (IMU): This was introduced in Oracle Database 10g Release 1. It increases DML and read-consistent-intensive operational performance by keeping as much undo as possible using in-memory objects, instead of traditional undo segments. My tests have shown a 21% CPU consumption reduction when using IMU with a read-consistent-intensive load.

The cursor is a fundamental object that is a complete executable representation of a SQL statement or a PL/SQL programmatic construct, which can be used and reused by any authorized session. Cursors must be created, locatable (that is, found by a search), destroyed (deallocated), invalidated, and reloaded. If any part of the cursor is not in the shared pool and is needed for any reason, that aspect must be reloaded, which does slow performance.

Developers typically have a good understanding of cursors because they have needed to specifically create, open, execute, fetch, and close cursors. DBAs commonly look at cursors as simply memory chunks related to SQL. However, this simplistic view inhibits our ability to create solutions to cursor-related performance problems. So, if you take the time to better understand cursors, you'll notice your performance solution options will significant increase.