There are a lot of factors that can affect the time: network traffic, what database you are running, database indexes, etc. The best thing for you to do is write a simple app that inserts several thousand records into the database using prepared statements, and several thousand using 'regular' statements. See how long each set takes. The difference may be negligable, or it may be irrelevant considering what else your real application does.
The performance considerations aside, there is still great value in using PreparedStatements for the ease with which you can work with
String and Date values, not to mention BLOB/CLOB objects or database-specific objects. Go with PreparedStatements.