In Russian http://lapitoop.ru/tuning-cache-openfire/
Tuning of cache Openfire
Openfire uses a cache for effective work.
But the size of a cache by default can appear is small, if at you in jabber many users/groups are connected.
Thus in broad gulls about errors you can see set of messages of such plan:
Cache Roster was full, shrinked to 90 % in 0ms.
For the decision of this problem you should add following parametres:
cache.group.size = 5242880
cache.group.maxLifetime = 3600000
cache.username2roster.size = 5242880
cache.username2roster.maxLifetime = 3600000
cache.userGroup.size = 5242880
cache.userGroup.maxLifetime = 3600000
cache.userCache.size = 2097152
cache.userCache.maxLifetime = 3600000
cache.groupMeta.size = 2097152
cache.groupMeta.maxLifetime = 3600000
To add new options follows through вкладку
Server-> Server Manager-> System Properties.
After updating of options it is necessary to restart service.