How to Fix Slow Excel 365 Performance and Disable Copilot
Question details
Users are experiencing severe performance degradation, slow scrolling, and unusually high memory usage in Excel 365, particularly with large workbooks, and are looking for ways to disable Copilot to restore speed.
- Product
- Microsoft Excel 365
- Device & OS
- not provided
- Scenario
- Editing large workbooks containing charts, shapes, annotations, and financial models that span hundreds of thousands of rows.
- Observed behavior
- Excel becomes exceptionally slow to scroll, edit, and render. Users observe excessively long load times and memory usage spikes (e.g., up to 5 GB for a 3 MB file), often attributed to Copilot and visual effects.
Save your current workbook and open your system's Task Manager to monitor Excel's memory usage before and after making these configuration changes.
Disable Copilot in Excel Options
Turning off Copilot is the most effective method for resolving sudden memory spikes and slow load times in recent Excel 365 builds.
Recent integrations of AI features can cause excessive background processing. Disabling Copilot frees up RAM for rendering large datasets.
Launch Excel, click on 'File' in the top-left corner, and select 'Options' at the bottom of the menu.
In the Excel Options dialog box, select 'Copilot' from the left-hand navigation pane.
Clear the checkbox labeled 'Enable Copilot', click 'OK' to save your changes, and then completely restart Excel.
Optimize Workbook Elements and Formatting
Large workbooks overloaded with unnecessary shapes, complex charts, and conditional formatting can cripple Excel's rendering engine.
Run Excel in Safe Mode to Isolate Add-ins
Third-party add-ins can conflict with Excel 365, exacerbating performance regressions in large files.
Experience Lightning-Fast Spreadsheet Performance with WPS Office
If Excel 365 continues to lag or consume too much memory due to bloated features, try WPS Office. It is a lightweight, highly optimized suite designed to handle massive datasets, complex formulas, and financial models with ease—without forcing resource-heavy AI overhead onto your system.
- 1. Download the App: Visit the official WPS website and download the free lightweight installer.
- 2. Open Your Heavy Workbooks: Drag and drop your large .xlsx files directly into WPS Spreadsheet without any conversion.
- 3. Edit Without Lag: Enjoy smooth scrolling and fast formula calculation, free from background bloatware.
Frequently Asked Questions
Why is Excel 365 suddenly using 5GB of memory for a small file?
Recent Microsoft updates that introduced Copilot and advanced visual effects can cause excessive background processing or memory leaks. Disabling Copilot in the Excel Options menu often resolves this issue instantly.
Can I disable Copilot in Excel Online?
Currently, the option to manually disable Copilot in Excel Online is limited for individual users, as it is generally managed by Microsoft 365 tenant administrators. You will need to use the desktop application for full control over these settings.
How many rows can Excel handle before it starts to slow down?
While Excel technically supports up to 1,048,576 rows, performance often degrades significantly around 300,000 rows. The exact threshold depends on the presence of complex formulas, volatile functions, embedded objects, and your computer's available RAM.
Do COM Add-ins make Excel load slower?
Yes, third-party add-ins initialize alongside Excel and can severely impact startup times and overall editing performance. Running Excel in Safe Mode is the best way to determine if an add-in is the root cause of the lag.
