SubscribeBug in 0.2.20110922
There exists a bug in the latest stable release, 0.2.20110922 (0.2.20110922_3), which causes objects to be cloned when a block of world data is loaded and unloaded, when eg. a player walks near it and then goes away, or joins and disconnects.
It cannot be seen initially, but will make performance worse over time and at some point will make at least servers quite laggy and even unplayable.
I intend to release a new version in the near future which has this fixed and not backport the fix to latest stable. If somebody very much needs 0.2.20110922 to be fixed, please tell and I will consider doing it.