You do not need to perform special tuning for Oracle RAC; Oracle RAC scales without special configuration changes. If your application performs well on a noncluster Oracle database, then it will perform well in an Oracle RAC environment. Many of the tuning tasks that you would perform on a noncluster Oracle database can also improve Oracle RAC database performance. This is especially true if your environment requires scalability across a greater number of CPUs.
Some of the performance features specific to Oracle RAC include:
Oracle Database dynamically allocates Cache Fusion resources as needed
The dynamic mastering of resources improves performance by keeping resources local to data blocks
Cache Fusion enables a simplified tuning methodology
You do not have to tune any parameters for Cache Fusion
No application-level tuning is necessary
You can use a bottom-up tuning approach with virtually no effect on your existing applications
More detailed performance statistics
More views for Oracle RAC performance monitoring
Oracle RAC-specific performance views in Oracle Enterprise Manager