Even when the two maps had no events the Underground map still had a big lag. The blank space is to allow future updates and to match floor coordinates. I guess that the lag is about some tile layers combinations plus being in a high coordinate number, as the Cave map has some lag in the lower floor, so I believe that a script fix is possible. I can divide the map in four and use scripts to make the teleports and the others things won't broke, but I wish to do this as last resort, if I don't find something better.