Hello,
I see some random performence spikes in my game. Using the profiler I encountered “Sempahore.WaitForSignal” is the cause. So what is this? And how can I track what causes this?
Check the timeline profiler for that frame and look at what the render thread is doing. The main thread is waiting for it to finish doing some work before it can move on.
WaitForSignal isn’t the root cause - what it is waiting for is the real culprit 
There is nothing under rendering. What should I’m looking for?
The spike is always some seconds after the scene finished loading, interrupting my cutscene.
Probably the GPU is rendering too much - it looks like the GPU workload is limiting the framerate.
Only one second during complete gameplay?
It seems to me the scene is not fully loaded. If I would hide the screen for some seconds before the cutscene starts, the player would never see the spike. So wait some seconds after Awake.
I tried several things:
Disable all shadows, disable all post procress, disable all skinned mesh, disable all custom scripts. Nevertheless I get the spike in first couple of seconds.