NHF – new heroes for Heroes V 3.1.

Does the Hafad script load with interface blocking? And how does it "lag"?

No. You load the map, and it starts to lag: it's almost impossible to rotate the camera. At that moment, the animation of objects on the map is slowed down. Well, the game just lags. If you comment out the Hafad script, the map will definitely work normally within a day.
The larger the map, the more it lags - probably just because there are more monsters on the map.