Excel taking too long on basic tasks and using 99,9% of CPU

Question

Hello, I have a macbook air M3 with 8GB RAM. Lately, my excel has been taking way too long (like 10/15 seconds) doing some pretty basic tasks, like opening 'more number formats', 'more borders', 'custom format', and other stuff like that. It is happening in all sort of files - it even happens in blank files, with no cells filled. I already updated it and tried some other tips that I found online but nothing seems to work. If someone could help me figure out what's wrong and how to fix it I would really appreciate it. Thanks!

Answer 1

Dear @Mariana Teixeira Francisco Pereira

Welcome to Microsoft Q&A Forum!

Based on your description, I can understand that you are experiencing Excel performance issues on a MacBook Air M3 with 8GB RAM, where even basic tasks like opening formatting menus take 10–15 seconds, and Excel uses 99.9% CPU, even on blank files. There are several reasons that may cause it:

1.Excel for Mac Optimization Issues:

• Excel on macOS may not be fully optimized for Apple Silicon (M3), especially with lower RAM.
• UI-related actions like opening menus can trigger rendering or sandboxing delays.

2.Add-ins or Background Processes:

• Even on blank files, Excel might load background services or add-ins that consume resources.

3.Corrupted Preferences or Cache:

• Excel’s user settings or cache files might be corrupted, causing slow UI responses.

4.macOS and Excel Compatibility:

• There could be compatibility issues between the latest macOS version and Excel updates.

Therefore, I have some suggestions that you can try to see if they can help you to improve it:

Please note that our support is limited to providing guidance based on official Microsoft documentation. Any third-party resources or references shared are intended solely for informational or consultative purposes. Microsoft does not guarantee the accuracy, reliability, or continued availability of third-party content, and we recommend exercising discretion when referring to such materials.

1.You may try starting Excel in Safe Mode:

Please kindly follow this article for detailed instructions: https://support.apple.com/en-sg/guide/mac-help/mh21245/mac
Reference: https://support.microsoft.com/en-us/topic/how-to-use-a-clean-startup-to-determine-whether-background-programs-are-interfering-with-office-for-mac-e99e92b2-f67e-b98d-b69f-d12236c53f2c

2.Clear WEF Caches on Mac for Excel:

You can try clearing these caches to see if it improves Excel’s performance:

• Quit all Office apps.
• Open Finder, then press Cmd + Shift + G to open Go to Folder.
• Enter the following path:

~/Library/Containers/com.microsoft.Excel/Data/Library/Caches/

• Look for folders or files related to WEF or Office Add-ins and delete them.
• Restart Excel.

Reference: https://learn.microsoft.com/en-us/office/dev/add-ins/testing/clear-cache

3.You may need to disable Add-ins:

Go to Tools > Excel Add-ins and disable any non-essential add-ins.

4.You can try testing on a New Mac User Profile:

• Create a new macOS user account and test Excel there.
• If performance improves, the issue may be likely tied to user-specific settings or cache.

Reference: https://support.apple.com/en-sg/guide/mac-help/mchl3e281fc9/mac

5.You should check the update Excel and macOS:

• Ensure both Excel and macOS are fully updated.
• Sometimes performance fixes are included in minor updates.

If these suggestions above do not work, you may try uninstalling and reinstalling the Excel app, please follow these instructions correctly (please kindly notice the bold note):

1.Uninstall and reinstall Excel: try uninstalling your Excel app and then reinstalling them. It is important that you download Office directly from the official Microsoft website, please do not download Office from your MacBook's App Store. (see steps and link below):

• Go to "Finder" > Applications > select Microsoft Excel > move to the Trash.
• Then, download Office directly from Microsoft's website, not Apps Store
• For more information, see the following link: Download, install, or reinstall Microsoft 365 or Office 2024 on a...

2.If you have already downloaded Office directly from the Microsoft website:

• You can downgrade: Uninstall your current version of Office.
• Visit the https://learn.microsoft.com/en-us/officeupdates/update-history-office-for-mac page and download the installation package for a stable older version, such as 16.100 or 16.99.

Additionally, to avoid interrupting your workflow, you can use Excel on the web as a temporary method while you are fixing the app. You can use the web version of Excel by logging in to https://www.office.com.

I hope this information can help you. Wish you a pleasant day!

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