Transform/transfer 50Gb - how to do it fast?

Hello!
I have an big table with 50Gb data, written som functions
that cleanup data and want to do something like this

insert into newtable
select id, func1(col1), func2(col2)
from oldtable;

I'm also plan to make newtable partioned (before insert).

But how could i get the insert as fast as possible?
Greetings
Bjorn D. Jensen

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