>Yes, it may be affected by the number and size of the fields. Try splitting the batches to, say, 500 records and compare the speed.
I move it to 300. This time, it took 0.8 to 1 second to insert 300 records at a time. Before, I had it at 500 and it took 3.5 seconds approximately. So, the time to process is better. This has helped.