Using Oracle 10.2.0.3 on SPARC?
There is a really useful patch if you've got db_block_checksum=TRUE (the default) to reduce the CPU utilization of the checksum routine. The patch number is 6814520 - annoyingly the bug report is hidden in metalink, but if you do a 'simple' search for the patch, provide the number, you'll be able to download the patch.
The patch is rolled into 10.2.0.4, but it's not documented as part of the patch notes.
