Running without battery, looking into ways to bypass the underclock

Hey, so my good old MacBook Air been serving me well through those 7+ years. Surprisingly, but it's still working perfectly fine... aside from battery, which just died of old age a couple months ago. It wasn't doing much good before, and then I discovered it works just fine without.

Eh, that's even better: I don't really need it anywhere beyond my bedside, connected to charger, and now it's almost twice lighter than before. Also it no longer overheats like crazy - yay! And not like I have choice anyway, since battery's expensive and, living in Russia, I can't get my hands on it by means other than ordering it from eBay and risking getting a brick instead.

The only problem being it works slower than it used to. Still tolerable, but really on the edge of it. I only need it to run video, watch streams, read twitter and such. But now pages open way slower than before and anything beyond 2 tabs will snap out of RAM and load again, streams won't run unless at 480p, etc.

Now, I've found a few solutions suggesting to move some system files (System/Library/Extensions/IOPlatformPluginFamily.kext, to be specific), but all examples of it working I've found were around 2013 year and about MacBook Pro. But just leeroying ahead and trying it blindly seems risky to me.

Can anyone verify it still has a chance to work in newer OS?

Right now I run 10.12.6 Sierra, and not updating it for a while because not sure it's a good idea without battery.