1. Bad Connection Management
2. Bad Use of Cursors and the Shared Pool
3. Bad SQL
4. Use of Nonstandard Initialization Parameters
5. Getting Database I/O Wrong
6. Redo Log Setup Problems
7. Serialization of data blocks in the buffer cache due to lack of free lists, free list groups, transaction slots (INITRANS), or shortage of rollback segments.
8. Long Full Table Scans
9. High Amounts of Recursive (SYS) SQL
10. Deployment and Migration Errors