Examine the SQL statement currently being run by the session experiencing waits to see what is causing the sorts.
Query V$TEMPSEG_USAGE to find the SQL statement that is generating the sort.
Also query the statistics from V$SESSTAT for the session to determine the size of the sort.
See if it is possible to reduce the sorting by tuning the SQL statement.
If WORKAREA_SIZE_POLICY is MANUAL, then consider increasing the SORT_AREA_SIZE for the system (if the sorts are not too big) or for individual processes.
If WORKAREA_SIZE_POLICY is AUTO, then investigate whether to increase PGA_AGGREGATE_TARGET. See “PGA Memory Management”.