prepared statement performance

Does anyone have some handy metrics of the performance advantage of
prepared vs unprepared statements?  I'm considering the case of an
application which has to make multiple queries/inserts (30-100) per
application transaction and which is currenlty generating the sql by
building the strings on the fly then passing them to the JDBC.  Can I
expect significant (ie worth the recoding time) performance increases by
converting the statements into prepared statements?

Thanks,
Sheer