Performance issues after 10gR2 Upgrade.

Fellas,

here is my situation: We have upgraded 11i database from 9206 and
10.2.0.2. There are various complaints on performance. When I digged
into it.. I found some init parameters whicha are supposed to be
removed in 10gR2..were not removed.

optimizer_features_enable  =9.2.0
optimizer_mode = choose.

We were using "Gather Schema Statistics" concurrent program to gather
statistics on application Schemas and dbms_stats on SYS and SYSTEM.
How do you guys gather stats ?

Im planning to remove these two parameters from Init file. I have
removed this in test instance... its now showing default parameters as

optimizer_features_enable = 10.2.0.2
optimizer_mode = ALL_ROWS

All the functionality is working... but dont know about performance...
as load is not there test or no one really uses test instance. I dont
know its implications...Can you someone suggest ?

This Optimizer mode change is a very big change..So Im afraid..what I
should hear during holidays.

I have created so many SQL_PROFILES so far in reaction to the
complaints.. Not sure if those SQL_PROFILES are still valid and
useful.. As optimizer is going to be chnaged.. would it be good idea
to remove and see?

Thanks
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