oracle forms 10g very slow on

We have been running oracle forms 10.1.2.3 application for 3 years without any performance problems. We have 400 concurrent users accessing the application using IE7 browser. The server team deployed IE8 on all the users workstations. Now all the users are complaining about performance problems. The forms application are terribly slow. After some research, we read that jinit is not supported on IE8. So we changed the formsweb.cfg to use the java instead. The 400 clients are now using java but the performance problem are still there. Does anybody know what the cause of the problem ? Is the problem IE8 ? Maybe java cache needs to be changed for IE8 ? The users are suffering and anoyed. Anybody has an answer ? Please help.

use java plugin instead of jinitiator.