Well, my comp is a little slow, so when I start building my zoo*, I usually get mabey twenty good-sized exibits in and my comp can then no longer handle all the movement...
*A breif veiw of my building style:
I start with one simple thing: A REALLY big food cort in the middle of the map with lots of space for additions later on. From there, I fill in the space on either side of the path, usually putting small animals in front. From there, I start adding 'Leaves' on, basicly little groups of exibits connected to a small path that connects to a main path that connects to the big food cort. I like to make the main path two to three sections wide, and circleing the perimiter of the zoo, conecting to the food cort in three directions. I like to go by biome then location when making these 'Leaves' in my zoo, but depending on what becomes available, I may go by size. I have never fully completed one of these zoos because of my computer's speed, but I plan on putting some up for dowload so someone can possibly finnish my creation.