When I had my guest count capped at 4,000 all ran smoothly as well. Guests were at 90% consistently, game flowed nicely with no build up of guests at entryway, and a great yearly profit. The issue simply lies with big zoos. It gets a bit laggy, but nothing terrible at 6k visitors. The issue is that all visitors come in hungry. thirsty, or some other mysterious need they need addressed ASAP. My zoo branches 4 directions from the main welcome center. All have big draw animals with the exception of the poor South American section of a tortoise and tapir. One has elephants, lions. the other Bison. When you look at where my guests have been it may end up being 3 habitats, an exhibit or two, and 7 shops. They have a hat on their head, a drink in their hand, and some fries in their mouth, but when they leave you can be sure they are going to complain that they did not have enough time to see the giraffes even though the monsieur frites they stopped at is on the Giraffe Paddock. The larger the zoo gets, the more upset they get because instead of wanting to see 2 animals my guests now want to see 5. Entirely realistic and fine, but with the time cap, and the amount of time they waste at shops, they have trouble seeing all the animals they would like because of time constraint and oddly random AI movement.
My issue for guests really comes down to this.
1. They come in with needs they need filled ASAP or they may turn around 5-10 minutes into their visit. This could be a simple fix. They could allow a second port of entry to avoid all guests hovering in one location, or simply have the guests be more willing to view animals on entry or to walk farther to get their soda.
2. They need to stop at so many shops that it takes up far too much of their time. Tamper down these needs. I never go to any location like a zoo and visit more shops or vendors than what I came to view. Museums, zoos, aquariums: I tend to visit the exhibits and animals more than shop for snacks. I may be wrong, but I believe most would be like this as well. A few stops for a drink or pretzel? Maybe a meal if I am starving, sure. Allowing them the ability to walk farther before being fed up a shop is busy would also help alleviate this issue. And tampering down their needs.
3. This wish I could have stayed longer to see & _. Well, you have twenty minutes left and every other comment & indicator is green...why do you not venture their on your way out of the zoo? This puts a lot of guests in the yellow or even red. Easy fix: Allow more time and have them utilize all of it.
4. Finally, and not really tied into this thread, but a strange annoyance for me, is the 35% of guests who complain when it snows or rains that they should have brought an umbrella or hope it is a small flurry. I have never once been mad at an establishment for it raining or any other weather anomaly on the day I choose to go.
I love the game; I just hope to be able to build a large, real world size zoo that is not crippled because guests are more focused on food & drink and time constraints make it difficult to see all animals.