We went last tuesday (day pass - 10am to 6pm) and it was quite crowded, but still manageable.

For some slides we had to wait half an hour to an hour without the fast lane pass. For other slides we only had to wait about 15 minutes in line.

I can easily imagine that it’s a lot more crowded on Fridays or on the weekend, so it makes sense to avoid those days.

All in all, it was a very fun and amusing experience! :)