It didn't lag much for me, but did crash several times.
I still don't understand your insistence on big layouts. What happens when you want to enter a house with your NPCs? Wont you need to place your characters in a house layout at that point? Or will all action happen outside? If you plan on creating a house in the same layout (but just way off screen and setting the players position there) then the lag problem will probably get worse.
Also, for the size of the layout 27MB seems extra big. Perhaps the resolution is too high on the graphics or maybe that's just how big these games get nowdays. Still the layout itself wasn't really all that big (most of it is black) so I'm not sure the problem.
I really think you should try splitting your layouts into smaller ones and then just respawing the players into the new layout.. yeah it is alot more work but you wont deal with lag issues (due to large graphics) because each layout will stay small.
I did find something that may or may not be causing your problems. You have some really messy else logic in your player movement event sheet. You could clean all of that up with just a couple events.
... did some more testing.. When I click off the map there is a whole bunch of lag with the movement.... Maybe there is some issue with the RTS behavior and the lag? Just throwing out crazy ideas.
EDIT... I changed the load textures from "application start" to "per layout" and it eliminated any lag for me. There still is the weird movement problem where you click on an area the player can't move to.