Random frame drops on start

Recently I posted a thread about bad performance:
https://forum.unity.com/threads/how...-to-enable-gpu-rendering.897971/#post-5898581

It looked like no lag in the game anymore, but I encountered something weird. When I enter playmode, sometimes no lag, sometimes it is very laggy. That happens when I change something minor as you can see in the following video. I started the game 4 times. First, no lag. After I changed a collider position and it started to be very bad. At the third run I changed an orange position and lag again. After that I disabled and re-enabled an random object form hierarchy and no lag again:

I also have 26 errors in console, but I said that I'll solve them later but I would like to know if they may be cause this "random" lag:




And another shord question:
What do you do when you feel demotivated with your project?

 

Thanks, now I have only 2 collapsed errors that I can't solve but no lag anymore, thank you.