I'm just as disappointed as I was when I first used a chromebook 4 years ago. It's slow, already crashed once - requiring a full re-install, the touchpad barely registers my finger, and it loses battery in a few days. Seriously if I leave it alone for a few days it drops from 100% battery to like 5%.
For $449 I'd rather buy a 5 year old macbook air than use another chromebook. I'm selling mine.
kextstat | grep -v com.apple
They're at /Library/Extensions/ and you can disable them like this:
kextunload /Library/Extensions/Some3rdPartyModule.kext
Even if it's not a kext it's good to keep tabs on kernel extensions you have installed. I hope that helps and apologies if you're already aware of all that.
Keeping batteries fully charged all the time makes a HUGE difference in their lifespan and ability to hold a charge. If you regularly let a battery run down under 25% you're directly contributing to the "won't hold a charge" problem.
At the fully-charged end of things, think of the batteries like latex balloons - if you repeatedly fully inflate them they're going to have problems sooner than if you just mostly-inflate them every time.