Reasons for performance issues:
1.VO query execution time is high or execution of same query multiple times.
2.Execution of so many queries on a command action/on page load. Due to Master-Detail-Deail-Details relation or multiple lookup items(drop downs) on single page.
3.More no.of database round trips due to low value of Fetch Size at VO level.
4.Unused iterators on page defs causing unnecessary query execution.
5.Many http requests due to incorrect range size value at VO iterator in page def.
6.Frequent passivation/activation of application module instances due to wrong settings.
7.Full page submit instead of partial http requests using PPR.
8.Fetch huge amount of data(rows and columns) on page causes huge JVM memory consumption and intern causes long running garbage collections.
Use table format for key columns and use form layout for remaining columns.
Change Access Mode in VO from "Scrollable" to "Range Paging"
9.Big scopes of managed beans consumes more memory. Use small memory scopes as possible.
10.Huge html content over http request/response causes performance problems. Use small names for UI components ids.
11.Many SOP and logging stmts slow down application performance.
12.Early Execution of taskflows in tab layout/popups and immediate load of table contents may slow down performance.
13.Early instantiation of VO and nested application module instances. Set Lazy Loading options in AM properties to defer instantiation.
14.Execution of static data VOs for each user/AM instance. Instead, group static data VOs into Shared Application Module causes only one time execution of static VOs per application.
