The CPU only spends time on "wait for event". Where is the real reason for low fps?

Hello. I am profiling my game because low FPS. I expect to see a clear name for the method or counter that runs the longest. But all time spends on “wait for event” like on screenshot

All counters such as Component Tick do not take much time to complete. What do I need to do to see the problem in the profiler?

About my game. It’s a real-time strategy game where I replace characters with simple actors because I’m trying to make it scalable. FPS drops when I add about 2000 actors AND they are all in the player camera. If I turn the camera so that they are not visible, then everything is fine. Obviously the problem is the number of actors, but I want to see where my time is being spent.

from my experience, It may be waiting for the GPU to draw the scene, before the CPU can process