use the parent world's player tag cache - maybe players needs to be a dict-like object instead, but it would still have to be shared here

infiniteworld.py

@@ -2815,6 +2815,7 @@ class MCAlphaDimension (MCInfdevOldLevel):
         self.filename = parentWorld.filename
         self.playersDir = parentWorld.playersDir;
         self.players = parentWorld.players
+        self.playerTagCache = parentWorld.playerTagCache
         
     @property
     def root_tag(self): return self.parentWorld.root_tag;