Question Upgrading my CPU

[OhGodItsJoel]

Hello,
I have an i5 6500 as my CPU. It might be dying down or something, as I've noticed a lot of performance loss, especially in CPU heavy games like CSGO. It is usually at 100% load and I my FPS has halved in a couple of months time (from 150 to 80 about). I am thinking of upgrading the CPU and adding RAM, not really looking to buy a new GPU. Of course I need to buy a new motherboard but I am quite sure my PSU will handle.
So, should I buy the i5 9600KF or Ryzen 5 3600X? Or is it worthwhile splurging a bit and buying the Ryzen 7, for continuity? Though I do not really do any kind of hard rendering or multitasking and mainly use the computer for video games. 90% of the time I play CS, which really needs good single thread performance and frequency, so would the Intel CPU be the best bet here? Also would I get that big of a bottleneck with an OC'd GPU and the 9600KF?
Thank you for your input.

My specs
i5 6500
GTX 1060 6GB
8GB RAM
520W PSU
GIGABYTE GA-B150M-D3H

 

[helpstar]

I doubt that your CPU is dying, more likely there is just a heat problem

run userbenchmark.com and post the http link of your result

Which 520W power supply brand and model is it exactly?

 

[OhGodItsJoel]

I doubt that your CPU is dying, more likely there is just a heat problem

run userbenchmark.com and post the http link of your result

Which 520W power supply brand and model is it exactly?

Running Core temp while gaming and the max temps have all been under 60C. And that is under 100% load, so shouldnt the temps be pretty normal, or even kind of low-ish? It is a non-K version so I only use the stock cooler.
My PSU is this one 520W Seasonic M12II EVO Edition, Full Modular, 80 PLUS Bronze, 40A 12v Single Rail, SLi/Crossfire, 1x120mm Fan, ATX, PSU

 

[helpstar]

run userbenchmark.com and post the http link of your result

 

[OhGodItsJoel]

run userbenchmark.com and post the http link of your result

Here https://www.userbenchmark.com/UserRun/27378522
Pretty much something you can expect from an almost 4 year old build, right? Only thing that is odd is the RAM thing. Should I investigate it further or is it normal?