[james7132]

There is still a game loop that runs every tick. The engine wouldn't work so well if we only responded to inputs as they come in, event pub-sub style.

As for ECS overhead, I've made it one of my top priorities to eliminate it wherever possible since it underpins the entire engine. We're at the point where most optimizations are saving a few tens or low-hundreds of microseconds per frame in your average game/app (i.e. lowering context switch costs from parallel system execution). If you're pushing below 60 FPS in your app, chances are the performance issues are not coming from the ECS, but some other part of the engine, or the app's own code.