There are situations like when assigning a member to a group or creating a new member for a group, listing users for a group, etc may result in poor or slow performance or even browser timeout with the 'Manage Users and Groups' portlet. These especially happends when a large number of users in a group or large number of groups exists in the ldap server. To avoid such conditions you might want to modify these configuration parameters http://www-1.ibm.com/support/docview.wss?rs=688&ca=portall2&uid=swg21247210 of the 'Manage Users and Groups' portlet based on your needs.
Login into WebSphere Portal very slow with Sun ONE LDAP particularly when the user belongs to a group that has about thousands of users or more and the ldap is not providing you the capability to evaluate the group memberships from user object directly (nsRole:nsRole for SunONE directory if groups are created with Role inside SunONE ). For this case, group membership searches are performed by locating the user on the member list of groups and for some reason the search takes long time even though the attributes are indexed like uid or even the uniqueMemeber. In order to fix the problem please ask youe ldap administrator to do the following in the ldap instance,
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