[pinneycolton]

Did you figure it out? If not, you may want to try choosing "All processes, hierarchically" from the View menu in Activity Monitor.

[xanderstrike]

I "solved" the problem by restoring a week old backup from before I'd upgraded to Sierra. All other things were equal, so the OS was the culprit. This is why good backups are important, never know when Apple's gonna screw you.