To view the performance do

alter system set timed_statistics = true.

then you could run the statspack utility, which could be found if you have 8i under

$ORACLE_HOME/rdbms/admin/statspac.doc

also you could run the utlbstat.sql to build the stats tables and then utlestat.sql to create a report. These above mentioned scripts would build only dynamic temp tables, on the other hand if you want to use the statspack, that would build some static tables which you could use for the future analysis too.

All the above said scripts were found under the above stated path on unix.

Sam