使用Java EE处理大量数据

We have a Java EE application that support Oracle, MySQL and SQL Server vendors. we are using a view model to view the fetched data from DB, also using pagination in the DAO model, and that's working good so far, but now we are working with millions of records like 10 millions, that cause to us a big problem since our application performance issues become very bad. After some investigations we had make we found that the order by in the query cause a big slowness in the DB level, but we still have to use it.We have a Java EE application that support Orac