Is this a bottleneck? i5 9600k with rtx 3060

[doodles099]

Hi, I wanted to write this post because I've been having a problem with my pc lately. Since quite some time I started noticing a decline in the performance on my i59600k. I used to run Read Dead Redemption 2 over 80 plus in places like Saint Denny and now I can't even get more than 60 in Valentine. I installed MSI afterburner to see what was wrong and I saw that the temps were too high. I changed the thermal paste and the temps were back to normal again but still performance didn't improve. I sent it to a PC repair shop and they told me there was nothing wrong with my PC and I'm frustrated because I can notice a significant downgrade in performance in a lot of games. Not only RDR2 and the common factor is the high CPU usage. I've been trying a lot of things to amend the problem but it has been useless since I see no improvement. I hope that somebody can help me with this because it has been pretty annoying and I don't know what to do anymore.