This is a "rant + fix" blog post. If you're looking for an interesting post, check out the other ones.
I own a Dell Latitude 3420. It works well, has good battery life, good keyboard, and lots of connectors (laptops today, ugh). I got the 1366x768 version though, so I bought a replacement 1080p display because 768p is... small.
From the beginning, there was a process constantly hogging up the CPU, idling at 25-30% usage, all the time. AC or battery, High Performance or High Efficiency mode, it was there. "WavesSysSvc":
I looked around and found that it was part of the audio driver. Why the hell would my audio driver take up a third of my computing power?!
Additionally, the headphone jack would just... refuse to work. The only way to get it to work was to have my headphones/speakers plugged in when the computer started, but that's not viable, so for all intents and purposes it was broken.
I searched, browsed the Dell forums, saw that a lot of people were having that same problem, with no answer from Dell apart from "try updating your drivers using SupportAssist" (my drivers were up to date).
Then, stumbled onto