The first few days/weeks, lunch lines are long... after a while it gets better.
Also, some teachers have incentives to be dismissed to lunch early so you can get in line and get your food faster (like if you did all your homework the previous day).
Does your school do lunch before or after play? I remember one year they switched lunch around where the kids play first and then have lunch because it was easier for them to transition to class since they were already calmed down.