If you have not done so already, I would recommend running the Validate & Repair tool on the data file from the File menu > File Operations > Validate & Repair option.
In the Validate File window that opens, click the top box to "validate file" and then click OK.
When the validation completes, a data log will open in Notepad, please let us know if any errors or issues are found/repaired, and when ready close and re-open Quicken.
Please let me know what you find!
-Quicken Tyka
most of the time it takes between 20 and 60 seconds to enter/change one line item. that means to categories one month's of downloaded transactions can take me more than 30 minutes. this is absurd.
@Katherine Cole Have you followed Tyka's suggestion, that's immediately above your post?
When you do TOOLS, Account List, do you have investment account(s) with a large number of transactions (presumably some/many are closed positions)?