Had the same issue on my 16" before I spilled coffee all over it and broke it. A lot of the time kernal_task would take up like 400% CPU, which was because plu

Had the same issue on my 16" before I spilled coffee all over it and broke it. A lot of the time kernal_task would take up like 400% CPU, which was because plugging the power cable into certain thunderbolt ports (on the left side) would overheat the computer. Even then I was consistently getting low performance, my fans were on all the time, and my computer was burning hot trying to power a 4k monitor and a 1080p monitor. After my 16" broke I got an M1 Mac Mini and obviously have not been having the same issues. Now my computer feels fast again. My old set up felt like I was using a Macbook Air or something.