How to use CTAS to optimum (speed) level?

create table new_lips tablespace lips_b storage (initial 900m next 50m maxextents unlimited initrans 10 freelists 10 ) parallel (degree 4) unrecoverable as select * from old_lips;

-we have already provisioned for enough space in initial extent
-we increased init_trans to 10 and freelists to 10
-used parallel degree (number of cpu / 2 )
-set unrecoverable to stop logging