When application is slow, then the root cause may be any where starting from Server till User Machine!
- Network Issue
- DB Issue
- Web Server Issue
- APEX Application Issue
- User Machine Issue (Browser)
To find out where the issue is.. you need to check
- Application is slow in all environments? DEV, TEST and Prod.
- Slow for all users?
- Slow for all APEX Applications or only one Application or only some pages in Application?
- When was Application working fine? What are changes done after which application became slow?
Try switching off components that you think are causing the issue, for e.g. if you think LDAP is issue, then make Application as "No Authentication" and see if this solves the issue. If you think issue is because of web-server (Web-logic Server) then set-up APEX Listener or EPG and see if it gets any thing better.
Once you know the root cause, then you can think of fix.
Great insight, thank you. I will related this to DBAs to check on the DB Link connections, this could be also part of it. The data have grown significantly and in this particular case there is only users for one module that are experiencing the extreme slowness. But there is only two users who uses this module who have been experiences this slowness. all other modules we can connect quickly but I tried it couple times, I did experience it and it is sooo slow. Thanks for the insight and I will go through it and figure it out.
Then I think the problem is with your specific pages (queries) and could be with DB links as-well as you have mentioned.
If your pages are report pages, then run the report queries outside APEX and see how much time they are taking. See explain plan and try to reduce cost of query.
See Performance Tuning Apex Applications from Sumneva. It's pretty old one, however it's still worth of having a look and most of things are still valid.