row lock waits

 Hi,
I would like to know what causes row lock waits on Indexes. Is that heavily stuffed block with less pct_free?

I have a non-partitioned table with 200 million rows and with 7 Indexes. Every day around 350K rows will be inserted to this table using Informatica job. Informatica statistics are showing writer is 99% busy. When I am looking into the issue I found that all the Indexes are experiencing row lock waits.

Please see the excerpt from v$segment_statistics.

OBJECT_NAME   STATISTIC_NAME                                                        VALUE
------------- ---------------------------------------------------------------- ----------
IDX_A         logical reads                                                       4870560
IDX_A         buffer busy waits                                                         1
IDX_A         gc buffer busy                                                            0