How to replace KEXT files in Monterey

I have a Macbook Pro 2015, which I mainly use for some light-weight coding and webbrowsing. It has unfortunately, for a long time, been incredibly slow. I read this solution posted here about replacing the kext files. However nowhere on the internet I can find an answer as to how to replace KEXT files on a legit macos install. Could someone inform me on how to obtain the El Capitan KEXT files and where to locate the KEXT files in Monterey so I can replace them? --- I have realised for a long time that my Macbook is extremely slow. It is not even possible to watch a youtube video on 720p without it causing lagging or other issues. I never really had issues with this before as I was not using the laptop often. However, due to circumstances I tend to use it a bit more lately and hence was looking for a solution, as the extremely slow speeds are not in line with what I am used to from this laptop. I tried reinstalling the OS multiple times, but without any results (there is literally only microsoft office and google chrome installed on that laptop at the moment). I did some research and noticed a lot of people are facing this issue, and the issue is not there with MacOS El Capitan. I also vaguely remember that the speed issue indeed arose after an update back in the day. I thought about just installing El Capitan, but since it is no longer supported assume that applications will no longer be supported for that OS. That is what led me to the story with the KEXT files. From my understanding of the linked post, the bug is in how the newer drivers operate with this specific Macbook. I was hoping that by reverting back to these old files, I would be able to gain some increases in speed on my Macbook. Another alternative I am considering if nothing comes from this is to order an m.2 + adapter for the Macbook and installing Linux on that, however I would like to not incurr many costs as I am only using the laptop around 1 to 2 weekends a month. Hence the rabbit hole I went down. I hope this clarifies the situation and provides the requested additional information