Your file, not your computer
Nine times out of ten, a slow Excel is a slow workbook. Formatting someone dragged past the last row, thousands of styles left behind by copy-paste from other files, conditional formatting applied to entire columns — all of it rides inside the .xlsx and renders or recalculates on every single action.
The two-minute diagnosis: open the file, press Ctrl+End and watch where the cursor lands. If it jumps thousands of rows past your data, the used range is inflated and Excel is hauling dead weight through every recalculation. File size is a weak proxy; the cursor tells the truth.
The usual suspects, in order of frequency
Every bloated workbook we have opened carried at least two of these. None of them show up on the file size alone, and all of them compound over months of small edits.
- Inflated used range — formatting or data once touched rows far below the real table
- Cell style pileup — thousands of custom styles, usually imported by copy-paste from other workbooks
- Conditional formatting on whole columns — rules re-evaluated over a million cells per edit
- Volatile functions like NOW, INDIRECT and OFFSET — the whole dependency chain recalculates on every change
- COM add-ins from old toolbars, PDF printers and BI tools that hook every open and save
- A saved AutoFilter or pivot cache that keeps a copy of the source data inside the file
Fixes that stick
Delete the rows and columns between your data and the inflated used range, save, and press Ctrl+End again — on old files that alone can cut opening time in half. Rebuild conditional formatting as rules over named tables, run a style cleanup macro, and disable COM add-ins you cannot name in File > Options > Add-ins.
For workbooks that keep growing, the structural fix beats cleaning: move the raw data into Power Query or the data model and keep the sheets for presentation. And take a hard look at inherited Personal macro workbooks — half of them still run code against files you no longer have.
Questions and Answers
Why does Excel get slower over time?
The workbook accumulates luggage — inflated used ranges, style pileups, whole-column conditional formats, old add-ins. Excel itself does not degrade; the file does.
How do I fix a slow Excel file?
Press Ctrl+End to check the used range, delete the dead rows and columns beyond your data, clean up styles and whole-column conditional formatting, and disable unused COM add-ins.
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