A
This issue can be caused by web pages in the Favorites list that sometimes or always prompt for access with a CAPTCHA. If you know that there are such pages among your Favorites, please remove them and see whether there's an improvement. Otherwise bookmark and remove all Favorites, then restore them one or a few at a time until you find the culprits. There may be more than one.
Credit for this observation to ASC member ethereum.
B
Please back up all data before proceeding.
Triple-click anywhere in the line below on this page to select it:
~/Library/Safari
Right-click or control-click the line and select
Services ▹ Open
from the contextual menu.* A folder named "Safari" should open. Quit Safari if it's running. One or more files in the open folder should have a name beginning in "History". Move those files, and only those, to the Desktop, leaving the window open. Relaunch the application and test. If there's no change, quit again and put the files you moved back where they were, overwriting the ones that may have been created in their place. Otherwise, delete the files you moved. The browser history will be empty. If possible, restore the deleted files from a backup that predates the problem.
*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select
Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You may not see what you pasted because a line break is included. Press return.
C
Please open the iCloud preference pane and uncheck the box marked Safari. Test. Then check the box again, if you wish. Post the results of the test.
