My true problem is I keep winding up with places that are to big and my computer freezes, I's there a way to I guess, trick the computer into working with a large area as if it where small?

My friends and I Have been playing D&D for years and have lately been trying to find ways to create this wonderful world we created, is there a way to use sketchup to make a new world created completely from fantasy and have it act like google Earth?