Depending on your database and schema, you might want to drop the indices on the table, to the inserts and then rebuild the indices. Also depending on your requirements, you might want to disable the DBI AutoCommit for the database (and statement) handles and commit at the end of your program run or at other convenient points during execution.

In the long run, there is nothing faster than the database supplied bulk loader program, sqlldr for Oracle, bcp.exe for MSSQL and whatever Postgres has. Postgres can directly import CSV files, for the others, you have to program the respective bulk loaders with the proper configuration file.