[Boron]

I am surprised that the main problem why large maps are unplayable has not even yet been mentioned:

The low unit limit!

I once tested it and iirc even Indy troops count towards it.
The unitlimit is only 32k-something.

This limit can even be too small for medium-sized games like on the cradle map but there the risk is really low.
On Faerun though it is very high.

If one of those Nations/Themes does well it is dangerous:
1. Ermor AE
2. Mictlan Blood heavy + using lots of slaves for patrolling
3. Pan CW/ Pan with Maenads
4. Ctis Dtombs
5. Ulm BF relying on Vampire counts

If Ermor AE controls e.g. 100-150 Provinces on Faerun (which is only 1/4-1/3 of the map) it should get at least 1000 freespawns per turn.
You see how easy they alone can exceed the unit limit