When loading from Oracle to Oracle then using the DIS SCD2 loader is sub-optimal as it doesn't do all the processing in-database. So if it's about performance then first step will be to implement a custom transformation for this.
What volumes are we talking about? Source, Target, Deltas (increments)?
As for CDC: Has it been turned on? Would you know where to source the data from and do you have access?
https://docs.oracle.com/cd/B28359_01/server.111/b28313/cdc.htm
http://www.dba-oracle.com/t_streams_change_data_capture.htm
Are you 100% sure that there is absolutely no column in your target table which would allow you to identify the deltas?
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