Office Apps Freezing

How to Fix Excel Freezing and Using 100% CPU

Maira Mehtab Sep 22, 2026 874 views

Question details

The user is experiencing severe performance issues where Microsoft Excel becomes unresponsive and consumes 100% of the CPU shortly after launching.

Product: Microsoft Excel
Device & OS: not provided
Scenario: Opening or using Microsoft Excel for regular spreadsheet tasks.
Observed behavior: Excel hangs or freezes completely while the system task manager shows it using 100% of the CPU resources.

Before you start

Before proceeding with the troubleshooting steps, ensure you have saved any open workbooks in other applications and check if your Windows operating system has any pending mandatory updates.

Solution 1Recommended

Run Excel in Safe Mode and Disable Add-ins

Starting Excel in Safe Mode allows you to bypass problematic add-ins or extensions that often cause high CPU usage and freezing.

Many performance issues in Microsoft Excel stem from outdated or incompatible third-party COM add-ins. Booting in Safe Mode helps isolate the issue by loading Excel without these extensions.

Open the Run Dialog

Press the Windows key + R simultaneously on your keyboard to open the Run dialog box.

Launch Excel in Safe Mode

Type 'excel /safe' in the input box and press Enter to start Excel in Safe Mode.

Access the Add-ins Menu

If Excel opens without freezing, go to File > Options > Add-ins. At the bottom of the window, select 'COM Add-ins' from the Manage drop-down list and click 'Go'.

Disable Problematic Add-ins

Uncheck all the add-ins in the list and click OK. Close Excel and restart it normally to verify if the CPU usage has dropped back to normal.

Identify the Culprit: If Excel runs smoothly after disabling all add-ins, you can enable them one by one, restarting Excel each time, to identify exactly which add-in is causing the CPU spike.

Solution 2

Repair Your Microsoft Office Installation

If core application files are corrupted, running an online repair can fix unexpected freezes and performance spikes.

Free Microsoft Office alternative

Experience Smooth Spreadsheet Editing with WPS Office

If Microsoft Excel continues to freeze and drain your CPU, consider switching to WPS Office. It is a highly optimized, lightweight alternative that handles large datasets effortlessly without overwhelming your system resources.

1. Download WPS Office: Visit the official WPS website and click the free download button to get the latest installer.
2. Install the Software: Run the downloaded executable file and follow the quick setup wizard to install the software on your device.
3. Open Your Spreadsheets: Launch WPS Spreadsheets and open your existing .xlsx files directly to continue your work without experiencing CPU freezing issues.

Lightweight design ensures low CPU and memory consumption even with complex spreadsheets.Fully compatible with Microsoft Excel formats including .xls, .xlsx, and .xlsm.Familiar user interface allowing for a seamless transition with zero learning curve.Completely free to download and use with essential spreadsheet features included.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Excel use 100% CPU as soon as I open it?

This is typically caused by conflicting third-party add-ins, corrupted startup files in the XLSTART folder, pending background calculations in a massive workbook, or a corrupted Microsoft Office installation.

Will I lose my unsaved work if I force close a freezing Excel?

If you force close Excel via the Task Manager, you may lose recent changes. However, Excel's AutoRecover feature usually attempts to salvage your file, which you can access in the Document Recovery pane the next time you launch the application.

How do I stop Excel from calculating automatically and freezing my PC?

Open Excel, go to the Formulas tab, click on Calculation Options, and select 'Manual'. This prevents Excel from recalculating the entire workbook every time a change is made, significantly reducing the CPU load when editing large files.

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