Quicken for Mac is slow or freezes when updating transactions on Mac OS 10.12 (Sierra)
The recent Mac OS upgrade, Sierra, can automatically sync files from your Mac system to the iCloud Drive. If your Quicken data file is in a folder that is set to be synced, (such as your Desktop or Documents folder), the Quicken application is unable to easily access your Quicken file to download transactions, causing Quicken to freeze.
To fix this issue
You can fix this issue by moving your Quicken file to a location on your system that is not synced to iCloud, or by changing your iCloud sync preferences. To update sync preferences, please follow the steps in this FAQ from Apple.