Maximum Roster size for a user in Openfire


What is the maximum size of roster for a given user. we see some degradation while adding above 3000 users in roster for a given user. Please let me know, Is there any parameters needs to be configured?. We have configured cache.userCache.size = -1, cache.username2roster.size = -1 and cache.username2roster.maxLifetim set to 3600000. Still it is degrading while adding users in roster above 3000 for a user. Please let us know any other parameters needs to be set.