Hi everyone!
Been a while since I've been here.

I have a db that I am upgrading from 9i to 11.1.0.7. Thankfully we are still in the testing stage. But the performance is much worse on 11g.

Environment:
HP-UX Risc 11.23
SAN disk.
Both the 9i and 11g databases are on the same disk.

I have a sample batch job that I have run on both instances. I have traced both. The issue seems to be most apparent for inserts/updates. Here is a sample ( I have removed the column names for security reasons):

9i:
Code:
update TABLE1  set .....
where
 ID=:b38


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse      819      0.09       0.08          0          7          0           0
Execute   1341      6.94       7.08          5       4812       5513        1341
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total     2160      7.03       7.16          5       4819       5513        1341

Misses in library cache during parse: 1
Misses in library cache during execute: 391
Optimizer mode: RULE
Parsing user id: 24

Rows     Row Source Operation
-------  ---------------------------------------------------
      2  UPDATE
      2   INDEX UNIQUE SCAN PK_TABLE1 (object id 18019)


Elapsed times include waiting on following events:
  Event waited on                             Times   Max. Wait  Total Waited
  ----------------------------------------   Waited  ----------  ------------
  SQL*Net more data from client                 915        0.00          0.01
  SQL*Net message to client                    1341        0.00          0.00
  SQL*Net message from client                  1341        0.00          0.29
  db file sequential read                         5        0.04          0.11
  latch free                                      1        0.00          0.00
********************************************************************************
11g
Code:
update TABLE1  set ....
where
 ID=:b38


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse      807      0.22       0.21          0          0          2           0
Execute   1370     25.95      25.23          3       4148       5776        1370
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total     2177     26.17      25.44          3       4148       5778        1370

Misses in library cache during parse: 1
Misses in library cache during execute: 384
Optimizer mode: ALL_ROWS
Parsing user id: 24

Rows     Row Source Operation
-------  ---------------------------------------------------
      1  UPDATE  TABLE1 (cr=3 pr=0 pw=0 time=0 us)
      1   INDEX UNIQUE SCAN PK_TABLE1 (cr=3 pr=0 pw=0 time=0 us cost=2 size=160 card=1)(object id 18019)


Elapsed times include waiting on following events:
  Event waited on                             Times   Max. Wait  Total Waited
  ----------------------------------------   Waited  ----------  ------------
  SQL*Net message to client                    1370        0.00          0.00
  SQL*Net message from client                  1370        0.00          0.35
  latch: shared pool                             10        0.00          0.00
  library cache: mutex X                        237        0.00          0.00
  db file sequential read                         3        0.01          0.01
********************************************************************************
As you can see.. it's the same plan.. but the 11g run spends a LOT of time on CPU.

Any ideas? Are there bugs I'm not aware of.. missing a init parameter

Here are the init parameters:
Code:
NAME                                     VALUE
---------------------------------------- ------------------------------------
_trace_files_public                      TRUE
archive_lag_target                       1800
audit_trail                              DB
compatible                               11.1.0
db_block_size                            16384
db_cache_size                            331350016
db_file_multiblock_read_count            16
db_files                                 1000
db_writer_processes                      4
disk_asynch_io                           FALSE
dml_locks                                2000
event                                    60 trace name systemstate level 16
job_queue_processes                      6
log_buffer                               2097152
log_checkpoint_interval                  10000000
log_checkpoint_timeout                   150
log_checkpoints_to_alert                 TRUE
max_dump_file_size                       UNLIMITED
nls_date_format                          YYYY-MM-DD
open_cursors                             600
optimizer_mode                           ALL_ROWS
pga_aggregate_target                     524288000
processes                                1000
recyclebin                               OFF
remote_login_passwordfile                EXCLUSIVE
session_cached_cursors                   600
sessions                                 1105
sga_max_size                             1073741824
shared_pool_size                         532676608
sort_area_retained_size                  1024000
sort_area_size                           5242880
statistics_level                         TYPICAL
tape_asynch_io                           FALSE
timed_statistics                         TRUE
transactions_per_rollback_segment        10
undo_management                          AUTO
undo_retention                           28800
undo_tablespace                          TBS_UNDO
Thanks for any help/insight you can give!