Insert row to table performance slow in 18c

WE have a new job in Oracle 18c DB, but the ODI insert sql seems slow, insert 20,000,000 row to temp table time need 1 more hours.

please help to assist what is the problem and how to tune the insert performance, many thanks.

attached two awr report as below:

1. awrrpt_1_3177_3178(commit 5000).html

for parameter set to 5000 commit

ADDM report too many Commits

Finding Name	Avg active sessions of the task	Percent active sessions of finding	Task Name	Begin Snap Time	End Snap Time
Commits and Rollbacks	1.65	59.38	ADDM:2611718358_1_3178	28-Apr-20 16:00	28-Apr-20 17:00

then change the commit parameter to 50000

2. awrrpt_1_3202_3203 (commit 50000).html

but found Unusual "Network" Wait Event in ADDM reoprt