There had been several threads about this, but since the search function is broken it's not as easy to find information as before. Anyway, after quick googling I found this, which is an old thread, so I'm not sure whether the limit was changed or not. Anyway, the maximum height is (or was) 1400 pixels and there is (was) no limit on the width of a room (a height of 1400 pixels is not a very large limit considering the fact that we now support 1024x768 resolution though).
For when a game becomes laggy I think that depends heavily on the player's systems but my guess is there shouldn't be much of a difference. Possibly memory usage is a bigger concern here, and note also that if a room is large and you move a character across a large room with complicated walkable areas the path finding routine can take longer to determine a path too.
For when a game becomes laggy I think that depends heavily on the player's systems but my guess is there shouldn't be much of a difference. Possibly memory usage is a bigger concern here, and note also that if a room is large and you move a character across a large room with complicated walkable areas the path finding routine can take longer to determine a path too.