Buffer busy waits occur when a session cannot access a needed block because it is in use by another session. The two most common causes are:
If buffer busy waits are significant, check the category of events being waited for on the Wait Activity Page.
If most buffer waits are for data blocks, it is likely that you need to create multiple free lists (using the FREELIST clause of the CREATE TABLE statement) for tables that are subject to very heavy concurrent inserts. If the leading category is for Undo Header or Undo Block, you may need to create additional rollback segments.