You're doing something serious aaand suddenly out of nowhere the fan starts screaming cause some cryptically named process decides right now is the time to get stuck in some loop
I use iStat and I don’t think a week goes by without being alerted to some process keeping a CPU core busy for half an hour. It would be reasonable for something sensible such as photo tagging or disk indexing. But the many background processes can get stuck, just look online for the flood of complaints.
corespotlightd, for example, uses >80% CPU (of a core, I think) for long periods of time. I’m talking _days_. The multiple store and iCloud agents also seem to get stuck. If you inspect a process, you can sometimes see it’s been doing something intensive for days or even weeks.
I get notified at 10 minutes of intense usage, but then I just keep looking and it’s really, really typical for a process to spend a few hours doing something, nuking the battery life of my laptop. I’ve been on macOS since 2008 or so and it’s not getting any better when it comes to zombie processed.