LoadingScreen.js kills scene load performance on heavy scenes

[Stinkfist0]

I have a scene with 12 200 entities and same amount of unique meshes. With LoadingScreen.js enabled, the scene takes forever to load (did not have the patience to clock this, I'd estimate maybe 15 mins or so?). LoadingScreen.js omitted the scene loads in some tens of seconds. Maybe change the loading screen to perform its update logic once a second or something instead of the current per frame basis.