copyManager Implementation :: in postgreSQL community Driver

there is a copyManager() implementation in community version JDBC driver.

From what I understand from client end, we provide the file as a fileReader and pass it on to the copyManager() instance.

I see the performance of this copyManager is not comparable to PSQL command line copy. Hence I wanted to know how differently is copyManager is implemented?

does copyManager implement the copy command (in server) for the whole file or, it does convert the file data into batches and implement copy command ?

Regards

Yogi