Q: photoanalysisd taking large amounts of cpu

It's normal for that process to take a long time. The amount of time is a function of the number of photographs in your Photos library.

Happened with me. Stopped after several hours. I assume it was reorganising/analysing the library somehow.

I've had the same issue.  I tried force quitting and it came right back.  It's a new process for organizing photos via Sierra.  Because it's taking so long I think it's a bug.  Just my humble opinion.

The system is processing your photos - when completed you'll be able to query your library in clever ways.

You can force the photoanalysis daemon to pause by opening the Photos app - it suspends

activity while the app is open. (If you minimise the app photoanalysisd will spring back to life, however.)

If you click on "people" in the left hand sidebar of the Photos app, it tells you how many photos it has processed, and how many are remaining.

While I do appreciate this is what it's doing -- Why in the world is Apple processing photos in the background WHILE I'm using my machine?!  This seems just absolutely insane to me, this going on while I'm TRYING to work with editing a 4k video...  Sure, even if the process is set to a low priority, it's still using up cpu cycles that could be more helpful toward WHAT I'm doing.  Why not do this when my computer is locked?!?  Even then, it should tell me it's doing something like that, what if I've got a render going?! /sigh.

Exactly! This is ridiculous. Just updated to Sierra yesterday. My mac was perfectly silent on Yosemite... now my mac is almost burning flames out of it's CPU... It'd take too much to notify the user what's going to happen so that I don't have to spend my time googling this problem... Apple common you can do it better. I hope this process won't take forever. Apparently, it's not a coincidence that multiple people are trying to get an answer to this....