Would you mind sharing what made you go with a stateful application server? I'm implementing a MMO game loop. Even though I am exposing the API as what amounts

Would you mind sharing what made you go with a stateful application server? I'm implementing a MMO game loop. Even though I am exposing the API as what amounts to a bunch of lambdas, under the covers, I am holding onto state and mutating it, basically for performance. EDIT: To put it another way, there is a level of abstraction at which my system is stateless. To implement that with enough performance, I have to hold onto state, so I can deliver data to the implementation of those abstractions in a timely fashion.