What to check in Statspack reports

Statements that are using the most CPU
Statements that are performing the most disk I/O operations
Statements that are having the most executions
Statements that are taking the longest time to execute (elapsed time)
LOOK FOR RESOURCE INTENSIVE SQL STATEMENTS
heaviest time consumer is CPU-related e.g. CPU Other or CPU Parse time or an I/O-related Wait Event e.g. db file sequential read or db file scattered read:
TOP Wait Events
TOP SQL STATEMENTS
containing the SQL statements with most buffer accesses
containing the SQL statements with most read I/Os from disk.
containing the SQL statements executed the most times.
containing the SQL statements with most soft parse calls.
containing the SQL statements occupying the most Library Cache memory.
containing the SQL statements with most versions (children cursors).
SQL WITH HIGH CPU OTHER TIME IN STATSPACK
SQL ordered by Parse Calls
HIGH DISK I/O WAITS
Identifying SQL statements responsible for most physical reads from the Statspack section SQL ordered by Reads has similar concepts as for SQL ordered by Gets.
SQL STATEMENTS WITH MOST EXECUTIONS
SQL STATEMENTS WITH HIGH SHARED POOL CONSUMPTION
This can help with Shared Pool and Library Cache/Shared Pool latch tuning