Oracle 11g - How to optimize slow parallel insert select?

Question

we want to speed up the run of the parallel insert statement below. We are expecting to insert around 80M records and it is taking around 2 hours to finish.

Answer 1

I can see 2 big problems:

1 - hint parallel (in select) NO NOT work, beacuse it should be like this +PARALLEL(T1,16)

2 - SELECT DO NOT optimal, it would be better if avoid expression NOT IN