Okay, more updates. Now I've noticed that I can "force" it to happen by opening any new program. This is NOT the only time it happens: it also happens from starting up or sometimes from being completely idle, but it happens EVERY time I open a new program. I can use the program eventually, but when it's opening, the spike happens.
Additionally, this last time I tried it, I noticed the same spike to around 86% in the CPU load, but also, a process "Kernel Task" showed up with 427% CPU usage. In fact, it's happening right now as I type this from another computer: the CPU load is spiking and the "Kernel Task" is at 359%. As soon as the "kernel task" goes down, the spike goes down, and the fans quiet down.
No spike in memory pressure, though.
This is all I got from entering that in the terminal:
Last login: Wed Mar 16 11:51:44 on console
Tests-MacBook-Pro:~ testuser$ kextstat | grep -v com.apple
Index Refs Address Size Wired Name (Version) UUID <Linked Against>
Tests-MacBook-Pro:~ testuser$