My project has had an issue with LoadLevelAsync (now LoadSceneAsync) where it freezes (blocking the main thread) when loading large scenes. This happens in the Editor as well as builds, including on other platforms. I've created a test scene that you can download here: https://drive.google.com/file/d/0B23oFFjKUdMAV21yWFI0VDVjOWs/view?usp=sharing This simple scene uses LoadSceneAsync while rotating a cube in Update. If the rotating cube stops moving, it is because the game is frozen. It also detects when there has been more than 50ms between frames and calls Debug.Log. Here is some example output: This has been an issue in our project for awhile now, even when we were using Unity 4. It seems to be an issue for others as well, but I haven't seen any solutions. Does anyone know how to get around this issue?