LoadLevelAsync Delay or Laging on Active?

I use AsyncOperation LoadLevelAsync for my loading scene.

IEnumerator LoadingLevel() {
async = Application.LoadLevelAsync("game");
async.allowSceneActivation = false;
yield return async;
}

But, when i active: async.allowSceneActivation = true;
...it's not smoothly, delay about two seconds to switch scene. Someone can tell me why? I want to it's active on 100%, not delay or screen freeze. Thank you.

 

async.allowSceneActivation = true this needs to be after yield, in your IEnumerator, to activate scene after its fully loaded. If it still freezes, check ya friggin' profiler.

 

What's the figgin' profiler?