Currently, Iron+ can /afk, keeping 41-81 chunks loaded even with no oneis actively playing, which creates unnecessary lag on the server. Also, it loads a specific shape.
My suggestion is to remove /afk, then add a Chunk Loader Plugin, increasing the max number of chunks that a player could have loaded based on rank. As an example:
Coal-1 Iron-4 Lapiz-9 Gold-16 Redstone-25 Emerald-36 Diamond-49
This will also allow chunks to also be loaded in a different configuration as well, such as a straight line, or even on different parts of the map, or some in Nether and some in End.
An example could be found here: https://dev.bukkit.org/projects/chunkloader.