kernel_task issue with imac 27" late 2015

Hello,

I have a iMac 27" late 2015, which within the last couple of months has been running super slowly (intermittently) to the point where the system is unusable and requires a force restart.

Using activity monitor, I've seen when the kernel_task is taking 300% of the CPU and causing everything to come to a halt.

I've read the apple support page regarding kernel_task and understand that its to prevent overheating of the CPU, but it occurs everyday. Facebook webpage could even trigger this. No longer able to play any games, they start off fast but then crawl to a halt.

I've tried the recommendations listed, reset the PRAM AND NVRAM etc.. nothing helps..

The computer is on my desk in my apartment that has AC, so its not in a super hot environment. plenty of space around for air circulation.

Any ideas what can be done to help this?

I realize that this computer is getting somewhat old (the new macos ventura isn't even compatible anymore!), however, Apple no longer makes 27" imacs. The only alternative would be a macstudio + the 27" display, which would run me around $5 (cdn).