12c vs 11g optimizer

Hi ,

we encounter this situation in  :

12.1.0.2 : bash duration : 5 hours (performances degradation for almost all queries).

11.2.0.3   : bash duration : 4 hours.

12.1.0.2 (  + alter system set optimizer_features_enable='11.2.0.3'; )  : bash duration : 4 hours !

Any idea to keep best performances and use 12c optimizer features ?

Please see attached file for 12c and 11g plans.

Best regards.

GD.