When it comes to database tuning, we usually don't provide any such recommendations due to the fact that the configuration would vary from system to system.
There are no generic recommendations from Clarity on tuning. However, based on Install guide:
Post-Install: Optimize Oracle 12c Performance
On local installations of Oracle 12c R1 or R2, you might detect a regression issue with Oracle 12c when ORDERED hint is used in structured queries. An Oracle bug in 12c R2 can degrade performance if the optimizer is set to 220.127.116.11.
For systems using Oracle 12c R1 (18.104.22.168), no further action is required.
For systems using Oracle 12c R2 (22.214.171.124), you can optimize performance by setting the optimizer to 126.96.36.199. We recommend applying this optional local fix.
Follow these steps:
From a command prompt in Oracle, enter the following lines:
sqlplus / as sysdba ALTER SYSTEM SET "_fix_control" = '17800514:0'; Exit;
Run the following command:
ALTER SYSTEM SET OPTIMIZER_FEATURES_ENABLE= '188.8.131.52' SCOPE=BOTH;
Verify that your Oracle 12c R2 initialization file parameters appear similar to the following example: