createrssfeed.action slow with large number of users in LDAP

[29148ms] - /devitwiki/spaces/createrssfeed.action
  [28743ms] - SiteMesh: parsePage: http://devoappsdev01:9101/devitwiki/spaces/createrssfeed.action
    [28740ms] - XW Interceptor: Before defaultStack: /spaces/createrssfeed.action (CreateRssFeedAction.execute())

.....
[137ms] - AOP: WikiStyleRenderer.convertWikiToXHtml()
          [1ms] - AOP: PageManager.getPage()
          [1ms] - AOP: SpaceManager.getSpace()
          [0ms] - com.atlassian.user.impl.delegation.properties.DelegatingPropertySetFactory_delegating_getPropertySet(USERNAME removed for privacy reason)
          [0ms] - AOP: PageManager.getPage()
          [0ms] - AOP: SpaceManager.getSpace()
          [0ms] - com.atlassian.user.impl.delegation.properties.DelegatingPropertySetFactory_delegating_getPropertySet(<USERNAME removed for privacy reason>)
...