VBA & Macro Problems

Fix Excel VBA Macro Running Slow After Windows 11 Upgrade

Maira Mehtab Sep 22, 2026 868 views

Question details

A complex Excel VBA macro that processes hundreds of thousands of records experiences a severe drop in execution speed after updating to a newer Windows version.

Product: Microsoft Excel
Device & OS: Windows 11 24H2 (and recent versions)
Scenario: Executing a large-scale data processing macro in Excel after a system OS upgrade.
Observed behavior: The VBA macro runs significantly slower than it did on previous Windows versions, despite the workbook and MS Office application versions remaining exactly the same.

Before you start

Before modifying your complex macro code, make a secure backup copy of your original .xlsm workbook. You can also temporarily disable Application.ScreenUpdating and Application.Calculation in your code to isolate the performance bottleneck.

Solution 1Recommended

Optimize VBA Performance by Using Memory Arrays

Rewrite the VBA code to process data directly in 2D arrays rather than instantiating individual row objects and storing them in collections.

Recent Windows updates can subtly change system memory management, making the creation of hundreds of thousands of individual objects much slower. The primary bottleneck is usually loading a worksheet, creating a custom object for each row, and storing it in a Collection or Dictionary.

To restore and even exceed your original macro performance, you should refactor the code to handle data entirely in system memory arrays.

Identify the Bottleneck

Review your VBA code and locate the loops where custom objects (classes) are instantiated for each row and added to a Collection.

Load Data into a Variant Array

Instead of iterating row by row, load your entire dataset into a variable at once using code like DataArray = ActiveSheet.Range("A1:Z100000").Value.

Process Data in Memory

Loop through the indices of the DataArray to perform your calculations and logic. This avoids the heavy overhead of creating individual objects.

Write the Array Back to the Worksheet

Once processing is complete, write the updated array back to the worksheet in a single bulk operation, which is exponentially faster than cell-by-cell manipulation.

Substantial Code Refactoring: Switching from an object-oriented VBA approach to an array-based approach requires significant code changes, but it is the most robust way to guarantee high performance on modern Windows environments.

Solution 2

Seek Specialized Code Analysis on Developer Forums

Share a minimal reproducible example of your slow macro with developer communities to find specific workarounds for your architecture.

Free Microsoft Office alternative

Try WPS Office for Efficient Macro Execution

If Windows updates are causing performance issues with your Microsoft Excel environment, consider switching to WPS Office. It provides a lightweight, highly optimized spreadsheet tool with robust built-in support for VBA and macros, ensuring your automated tasks run smoothly without expensive subscriptions.

1. Download WPS Office: Install the free WPS Office suite from the official website.
2. Open Your Macro Workbook: Launch WPS Spreadsheet and open your existing .xlsm file without needing conversion.
3. Execute Your Macros: Navigate to the Developer tab and run your existing VBA code in the highly optimized WPS environment.

Fully compatible with Microsoft Excel formats (.xlsx, .xlsm, .xls)Built-in robust support for running complex VBA and macrosLightweight architecture for faster loading and processing speedsFamiliar user interface allowing seamless transition

microsoft office alternative - wps office

Frequently Asked Questions

Why did my Excel macro suddenly get slower after the Windows 11 update?

Changes in system memory management, background services, and security protocols in recent Windows updates can affect how Excel handles frequent object instantiation. Scripts that create thousands of custom objects or heavily use Collections tend to suffer the most from these changes.

Are arrays faster than collections in Excel VBA?

Yes, processing data directly in arrays is significantly faster. Creating individual objects for each row and storing them in a collection introduces massive overhead, whereas arrays handle data purely in memory with minimal system resource consumption.

Can I simply roll back my Windows update to restore macro speed?

While rolling back your Windows update via System Settings can temporarily resolve the issue, it is not recommended as it leaves your device vulnerable to security risks. Refactoring your VBA code to use arrays is a sustainable, long-term fix.

Excel & Data Problems