(2018.3.11f) Strange gradual slowdown

So, I just finished the first boss in my current project and I just founded a very strange slowdown in my game during test gameplay.

Starting in the first stage, everything is smooth and usable, until I reached the third stage, the game gradually slowing down. Even with using Resources.UnloadUnusedAssets didn't work well; it still slowing down no matter what.

Tried to make a test build, but it's gradually slowing down at the fourth stage. Is it Unity's having a bug or my stages are not optimized enough?

Just in case, I brought my project source for your further inspections:
https://drive.google.com/file/d/16gF538UkdKoxQP-1EVj5gk79RoaF-Lwj/view?usp=sharing

 

Unity comes with a tool that allows you to measure how expensive something is. This tool is called a "Profiler".

Profiler overview
https://docs.unity3d.com/Manual/Profiler.html

Introduction to the Profiler
https://unity3d.com/learn/tutorials/topics/interface-essentials/introduction-profiler

You can measure performance while it's fine and while it's slow. Then you can look at both captures to figure out where the performance decrease occurred.

 

Well, I forgot to tell that I've checked before. It seems that it has something to do with the memory usage (Total Allocated), perhaps memory leak?

 

If on mobile watch out for thermal throttling. Otherwise just profile. Learn how to use the profiler properly, it's not just bars and graphs.

 

I want to know, what else are the factors of slowdown in Unity, besides incompatible hardware and improper memory usage?

 

OK, based on what I witness, looks like my audio system was causing the game to slow down, since it suddenly uses too much CPU.