This is especially true with methods that take a Player as an argument, which is normally the case.

Is it possible to make the Player (at the very least) a piece of data the Spell (or maybe SpellBook) keeps internally, so we don't have to pass it around so much? It can very quickly accumulate and kill servers with limited amounts of memory.

I don't consider kilobytes to be a lot of data. Even in a very large server with hundreds of players it would probably only be a few megabytes or less and if a server can't handle that much extra memory, it shouldn't have that many players in the first place.

Also, I don't think there's any other way to do it that would use less memory. Maybe there would be less memory used on rundata, but more would have to be used elsewhere.

Very well then. I'll label this wontfix and close it.