I´ve 800 users in some roster groups and everytime I delete a user it takes a minute or more and the CPU reaches high load.
I guess it´s because it sends some message to all his contacts.
I´ve found a workaround for this, that makes me believe this could be optimized in the code:
If I first remove the user from the rosters group and only after I delete him( without him being in a group) its fast and without any cpu load.
Hope somenoe can take a look at this and improve openfire.