Question CPU running 100% usage and suttering

May 1, 2020
CPU: I5-7600k (currently not running OC)
Motherboard: MSI Z270 Tomahawk
RAM: 16GB 3200Mhz (Corsair Vengance)
GPU: Asus Expedition 1070 (never been OC)

So i mainly started noticing this after recently wanting to play some Borderlands 3, a game i ran when it lauched with no problems. The game ran perfectly smooth, but now my CPU is more or less at a constant 100% usage while running it.

I now tried to run Borderlands 2 instead but my CPU hits 100% usage even in that.
Im getting constant stutters while playing more or less anygame on my pc.

I also started noticing random spikes to 100% while watching youtube videos, or even just browsing the web (even just standing idle on random sites)

I have tried factory resetting my pc but its still doing it.
I have tried running antivirus but it cant find anything.

Everything was bought around September 2017

I have only overclocked through the default MSI Game Boost function through my BIOS, since im not much of a tech nerd, so i didnt dare play with it manually.

Is my CPU just old and needs to be replaced or is something wrong with it?