Things to improve (from what I saw on my flight from KORD-EDDH)
1. Parking management. The airport never got full, KORD is a huge airport, and as such can hold hundreds of aircraft. I think if you guys added a stand with the slot and the times that you can use that stand (11:30-12:10, etc) it could increase the amount of aircraft that are able to depart. By assigning non-slots stands and runways it could also lead to more takeoffs (especially in KORD since it has more than 2 parallel runways).
2. Not much a vatsim issue but pilot related, people were connecting 20 mins prior to thei