Hi Kazuki,
You can use settings table IUUC_PERF_OPTION to optimize the performance of the initial load of the individual tables
No of Parallel Jobs - The maximum number of jobs that will be used for loading the table
Please refer this guide page 46.
SAP HANA Configuration Guide Trigger-Based Data Replication
Using SAP LT (Landscape Transformation) Replication Server for SAP HANA
I hope this helps.
Regards,
Naveen.