optimizing mass inserts and updates

Hi, I'm converting data from Oracle7 to Oracle10 and the tables and the data change a lot. The main conversion is done by insert-select (dynamic plsql) from imported old tables and that works fine and pretty fast even for big tables (more than 1 million rows), but extra upates that are often needed are a little bit slow. So I'm wondering how to speed them up. I'm going to