Sierra slowed down my mac and it keeps freezing sometimes

I have had the same problem for almost a week since I installed Sierra on my Late-2013 MBP Pro (15" retina). The system would freeze or hang in different ways (some time one app would be non-responsive with beach-ball and I could click on other open apps and soon everything would just freeze and the only way would be to hit the power switch). It happened mostly in Safari, but then I could see it with Chrome as well as other non-browsing applications too.

This happened 10-12 times a day - very frustrating. I took the Time machine back up since I had updated many files.

I have painfully gone back to El Capitan (unfortunately, I could only restore from my last El Capitan backup and not do any migration from the Sierra based TM backup). For the last 36 hours no crashes and the system feels much faster.

Hope this helps - I'd advise to go back if possible.

Back up your Mac if you have not done so already. To learn how to do that please read https://www.apple.com/support/backup/. To learn how to use Time Machine read Use Time Machine to back up or restore your Mac.

Then, shut down your Mac and restart it in "Safe Mode". To learn how to do that please read: Try safe mode if your Mac doesn't finish starting up. Compare how your Mac works in Safe Mode to how it has been, and describe your observations in a reply to this Discussion.

Then, restart normally. If the same problem returns, please read the section If an issue doesn't happen in safe mode for Apple's recommended actions.

Finally, you can temporarily create a new User Account, and log in to that account to determine if the problem also exists when logged in to that Account. To learn how to do that read How to test an issue in another user account on your Mac. When you are finished troubleshooting, you can remove the temporary User Account by following these instructions: macOS Sierra: Delete a user or group. Before removing it, confirm you don't need any of the files you might have created in that Account.

Let me know what you determine.

I had this same issue. Finder was really slow and sometimes never opened. My fix was signing out of iCloud. As much as I love the new iCloud feature in Sierra it made my system, especially Finder really slow and unresponsive. As soon as I signed out it Finder was back to normal working as it should. I hope Apple fixes this because it really is a great feature for me. I hope this helps you or someone else.