Help define true bottleneck? Specs Below?

[UTFapolloMarine]

So i got an average of 41fps, lows 6fps but highs 161fps+, i wanted to know, since not everyone will get the same outcome, some systems are more stable some are not, i ran it on extreme mode just having fun. What is the bottleneck here? Why did i drop to 6fps but get 161fps high? Is it the engines fault, or is it not optimized for 16 threads or even 8gb vram? Lets talk about bottleneck either its engine or hardware!

SPECS:
RYZEN 2700X 8 CORES 16 THREADS
RX 5500XT 8GB
32GB RAM 2667MHZ