Query performance issue after migration

Hi Experts,

I migrated our E-Business Suite Database from 10.2.0.4 32-Bit to 11.2.0.3 64-Bit last month.

For some queries, performance is worse after migration. 

Some queries do not complete, where they were used to complete within seconds.

I can use following workaround to execute these queries in migrated database. But it's not practical as there is so many affected custom queries.

ALTER SESSION SET OPTIMIZER_FEATURES_ENABLE='10.2.0.4';

Please help me to track down the issue.

Thanks,

Lakmal