Format Cells now takes 10 seconds to load

MacOs 26.1 has just about fixed this. still takes a second or two to get the dialog box.

Much better,

running:

Mac Excel Version 16.104 (25110230)

macOS 26.1 (25B78)

Tahoe 26.1 just released almost back to instant, on 2 second delay now... much better

I can confirm the same issue. I downgraded to v16.100 and the problem is gone. I wasted quite a bit of my time on this... Now, how are we going to be comfortable upgrading later to know the problem won't return as soon as we do so! All of these other solutions like corrupted files, etc... are just generic answers and unhelpful. If anything they make you waste more time. Frustrating...

Hello,

Thank you for reaching out to Microsoft Q&A forum.

Sorry for this unwanted experience regarding the slowdown of Format Cells dialog on your Mac. The possible causes are problematic add-ins, corrupted application preferences, or issues within the workbook itself. Here are some workarounds you can try to resolve it:

Test in Safe Mode

Launching Excel in Safe Mode helps determine if the issue is caused by an add-in. Safe Mode starts Excel without any add-ins or customizations.

• For Mac: Hold down the Option key and double-click the Excel icon to open it, or open the app from your Applications folder while holding the Shift key.
• If the Format Cells window opens quickly in Safe Mode, an add-in is likely the cause. Re-enable your add-ins one by one (via Excel > Add-ins) to identify the problematic one.

Reset Excel Preferences

Corrupted preference files can cause various performance issues. Resetting them can often help.

• Quit Excel completely (Command + Q).
• Hold down the Option key and click on the Go menu in the Finder. Select Library.
• Navigate to the Preferences folder.
• Look for and move these files to your Desktop (or delete them):
  • com.microsoft.Excel.plist
  • Any file named "Microsoft Excel [version].plist" (e.g., "Microsoft Excel 16.plist")
• Restart Excel. It will create new, default preference files.

Check for and Install Updates

Microsoft regularly releases updates that can fix bugs introduced in previous versions.

• Open Excel and go to Help > Check for Updates. Follow the prompts to install any available updates.

Check Your Workbook with the Performance Tool

Excessive formatting can slow down all operations in a workbook. Use Excel's built-in tool to check for this.

• In Excel, go to the Review tab and select Check Performance.
• The tool will show you how many cells can be optimized. Use the Optimize All or Optimize Sheet button to clean up unnecessary formatting.

Suggested Next Steps

If the issue persists after trying the steps above, here are some additional avenues to explore:

• Create a New User Account on your Mac: Testing Excel in a new user account can determine if the problem is with your main user profile's system configuration.
• Check File Location: If your workbook is stored on a cloud service like OneDrive, try saving a copy locally on your Mac's hard drive. Some users have reported better performance with locally stored files.

Hope this helps. Feel free to get back if you need further assistance.

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