I use a like 20-30 years old PC fromĀ my dad and when I use mineimator brdf, I have 6 FRAMES PER SECOND WHILE JUST HAVING A SWORD IN MY TIMELINE. I think you're using too many things at once in your project, try to make less objects in your project.
No, having lots of objects does not cause the problem. The problem is that when rendering is on, the screen becomes pitch black, and there were no objects in the timeline, NO OBJECTS.