In order to improve the performance of the personalization (PzN) function in WebSphere Portal, the PzN results can be cached. Otherwise the LDAP and the Portal database is accessed excessively. There are different forms of caching within PZN - resource collection caches, visibility rule caches, and others. However, most are surprised to find that Portal disables the PzN visbility cache by default.
If your production (or performance sensative) Portal uses PzN, then you should definitely enable the PzN cache. If not, both the LDAP and the database are excessively accessed. Note that visability rules in the theme use PzN.
The cache is enabled via a file. There is one of these files per node. Therefore, you must update one file on every node and then restart the cluster for the change to take effect.
The file is /opt/IBM/WebSphere/wp_profile/PortalServer/config/config/services/PersonalizationService.properties.
Set the property "rulesEngine.attributeBasedAdmin.enableCaching" equal to "true". This will enable the Portal PzN caching in Portal.
In addition, there is an undocumented property "rulesEngine.user.nestedGroupLookup" which can be set to false to speed up PzN. However, this should only be done if (and only if) nested groups are NOT used in the authorization ACL lists in Portal.