I didn't see your update about the grid until now. If you have patient players, it should be fine; after all, what is to prevent us from doing something else, like opening a second SEIV game, while your mod loads?
With a few programs running (Firefox and Thunderbird), it took me five minutes to load SEIV, and nearly thirty seconds to open the Design window. My computer has an Athlon XP 1500+ and 3X256 in memory (not sure what sort of memory).