Excel Performance Problems

How to Fix Excel Using Only 51 Percent of CPU Resources

Camila Milosovich Oct 1, 2026 870 views

Question details

The user is experiencing a performance limit where Microsoft Excel only utilizes roughly half (51%) of the available CPU processor threads when calculating large financial workbooks.

How to Fix Excel Using Only 51 Percent of CPU Resources

Product: Microsoft Excel
Device & OS: not provided
Scenario: Calculating complex financial workbooks containing large datasets, intricate formulas, and heavy dependencies.
Observed behavior: Excel fails to utilize 100% of the available processor threads, capping overall CPU usage around 51% and causing calculation delays.

Before you start

Before troubleshooting, create a backup copy of your workbook and remove any confidential financial information so you can safely test calculation performance.

Solution 1Recommended

Enable Multithreaded Calculation in Excel Settings

Verify that Excel's internal settings are configured to allow the use of all available processing threads on your machine.

By default, Excel is designed to use all available processors. However, custom settings or previous crashes might have restricted the application to a single thread or a limited number of cores.

Open Excel Options

Launch Microsoft Excel, click on the 'File' tab in the top left corner, and select 'Options' at the bottom of the menu.

Navigate to Advanced Settings

In the Excel Options dialog box, click on the 'Advanced' tab on the left pane.

Enable All Processors

Scroll down to the 'Formulas' section. Ensure that 'Enable multi-threaded calculation' is checked, and select 'Use all processors on this computer'. Click 'OK' to save your changes.

Enable Multithreaded Calculation in Excel Settings

Restart Required: After changing multithreading settings, restart Excel and trigger a manual recalculation (F9) to see if CPU utilization increases.

Solution 2

Optimize Workbook Formulas and Dependencies

Resolve structural limitations in your workbook that force Excel to calculate sequentially rather than in parallel.

Solution 3

Create a Sanitized Sample File for Support

Isolate the issue by providing a stripped-down version of your file to IT administrators or Microsoft Support.

Free Microsoft Office alternative

Try WPS Office for High-Performance Spreadsheet Processing

If Microsoft Excel continues to struggle with multithreading limitations and CPU caps on your complex workbooks, consider using WPS Office. WPS Spreadsheets is a highly optimized, lightweight alternative that excels at handling large datasets and complex calculations quickly.

1. Download and Install: Download WPS Office for free from the official website and complete the installation.
2. Open Your Workbook: Launch WPS Spreadsheets, click 'Open', and select your heavy .xlsx file.
3. Experience Faster Calculations: Perform your regular calculations to experience smoother performance and optimized resource utilization.

Fully compatible with Microsoft Excel formats (.xlsx, .xls, .csv)Lightweight architecture optimized for speed and system performanceSeamless processing of large datasets without unnecessary CPU limitsFamiliar user interface ensures a zero-learning-curve transition

microsoft office alternative - wps office

Frequently Asked Questions

Why does Excel only use a fraction of my CPU during calculation?

Excel builds a 'calculation chain' based on formula dependencies. If Formula B requires the result of Formula A, Excel must calculate them sequentially. This prevents the application from dividing the workload across all available CPU threads, often resulting in only 30% to 50% CPU usage on multi-core processors.

What are volatile functions and how do they affect CPU usage?

Volatile functions (such as OFFSET, INDIRECT, RAND, and TODAY) recalculate every time any change is made anywhere in the workbook. Overusing them forces Excel's calculation engine to constantly process data on a single thread, causing severe lag and preventing efficient multithreading.

Will adding more RAM fix my Excel calculation speed?

Not necessarily. Adding more RAM allows you to open larger files and run more applications simultaneously without crashing. However, if your calculation speed is bottlenecked by CPU thread limits and complex formula dependencies, increasing RAM will not speed up the calculation process.

Can I force Excel to use 100% of my CPU?

You can ensure Excel is allowed to use all processors by checking 'Use all processors on this computer' in File > Options > Advanced > Formulas. However, you cannot force 100% usage if the structural design of your workbook requires sequential, single-threaded calculation.

Excel & Data Problems