Here is an example I wrote a while ago on loading soft pointers into hard ones:
The example shows how to do this asynchronous. There are 2 ways of loading something. Sync and async. Async just means it is parallel to whatever you are doing so that you don’t block the entire game until it is loaded. It will load while you do other things.
Ok 
. You can usually make an estimation but in the end very specific cases will pop up that kill performance and you can measure those in the debugger / profiler . I’ve had cases were loading 5000 pieces of foliage were fine, ± 400 static meshes (just cubes) screwed FPS until I put them into an InstancedStaticMeshComponent, and a case were a hidden main menu was screwing FPS because UE’s implementation of UI does a ton of cursor operations on invisible widgets. You won’t see it coming until it happens, then you fix it .