Parsing times of Oracle 12.2. depending largely on OPTIMIZER_FEATURES_ENABLE

Currently I make our internal certification of our programs with Oracle 12.2.0.1 Standard Edition on Windows.

When comparing with Oracle 12.1.0.2 I have seen that the parsing times of the statements are much longer. For a mix of some statements with repeated executions the executions are 15 to 30 % longer.

What is strange is the dependency on the switch OPTIMIZER_FEATURES_ENABLE.

Using an ALTER session SET OPTIMIZER_FEATURES_ENABLE = with values of 12.1.0.2, 12.1.0.1, 11.2.0.3 returns to execution times similar to the edition 12.1.0.2.

Using statements that are already parsed give similar execution times for both Oracle versions. The test statements I use is a mix of different selects (simple, complex) and procedures that contain simple and complex select statements.