Yes we've had that problem previously when we're still using a lower specs server [1GB RAM / Intel Xeon].
The memory was insufficient that time, so we decided to transfer Openfire to a much higher specs.
Right now, the server we're using has 8GB of RAM with the same processor.
If you're still having a problem with memory leak even if it's installed on a higher memory server, I think there must be some sort of application or program that runs in the background and eats a lot of resources rather than java.
I'm not sure, but my understanding is, the more the users connected, openfire requires more memory.
Since then, we never had this memory leak problems anymore.
Let's wait for someone who resolves this issue