Ok

v$waitstat:

data block wait is highest
In v$sysstat, do u see high dirty buffers inspected , increase DBWR processes.

v$system_event : db_file_sequential_read is highest, did u see high ebough buffer busy waits and buffer deadlocks.
Increase Freelists .
Also in V$latch_children , check for cache buffer chains , are sleeps divide properly on all chains, if no get ADDR of that chain.


select dbarfil,dbablk,count(*)
from x$bh
where hladdr='838E85EC'
group by dbarfil,dbablk

Get the block(s) with high counts
and from dba_extents , get the object name.

Increase Freelist or change sql code.

Take Care
GP